Expression of NMDA channels on cerebellar Purkinje cells acutely dissociated from newborn rats. 1. Conflicting evidence exists concerning the expression and properties of N-methyl-D-aspartate (NMDA) receptors on cerebellar Purkinje cells during development. We used whole-cell and single-channel recording to examine NMDA receptors on acutely dissociated Purkinje cells from newborn rats (postnatal day 0-4). 2. NMDA channels were present on > 80% of identified Purkinje cells and had pharmacological and single-channel properties that were indistinguishable from NMDA receptors on other neurons. In particular, responses were glycine-dependent and Mg2+ produced flickery open-channel block. 3. Our results demonstrate the transient expression of NMDA receptor/channels on Purkinje cells early in development. As NMDA receptors have been implicated in developmental plasticity in other regions of the CNS, a similar role is feasible during climbing fiber innervation of Purkinje cells.


Sacrococcygeal teratoma in Sweden: a 10-year national retrospective study. Thirty-two children with sacrococcygeal teratoma have been treated during the last 10 years (1980 to 1989) in Sweden. A retrospective study was performed in four departments of pediatric surgery that treat sacrococcygeal teratomas in children from the whole of Sweden. Prenatal and perinatal histories were reviewed together with interval to diagnosis, Altman classification, histology, and serum alpha-fetoprotein. Details of surgical management +/- adjuvant chemotherapy and outcome of patients were also documented. In 8 patients the teratoma was diagnosed prenatally by ultrasonography and there was one postoperative death in this group. Multiagent chemotherapy was used in all but one of 11 patients with malignant teratomas (in 8 of them a cisplatin, bleomycin, vinblastine combination). Only one patient with a malignant tumor treated by single-agent chemotherapy died, 8 others were still alive and tumor-free after 1 to 9 years (mean time, 5.4 years). Two patients developed late relapses and were treated by surgical resection. Metastases occurred in five of the 11 malignant tumors, one at presentation and in four patients 10 to 29 months following surgery. All relapses had distant metastases as well as local disease. Serum alpha-fetoprotein was used in monitoring some of these patients.


Median sternotomy wound dehiscence: a retrospective case control study of risk factors and outcome. Over a 5-year period from 1985 to 1989, 2760 patients underwent open heart surgery at the University Hospital of Wales. Of these, 44 (1.6%, 35 men, mean age 61 years) developed median sternotomy dehiscence 2-40 (median 9) days after surgery. Infection was an associated factor in 18 patients (41%) and Staphylococcus aureus the predominant isolate in seven of those. Thirty-seven patients underwent rewiring of the sternotomy wound and seven patients underwent debridement, removal of wires and delayed closure. In those undergoing rewiring, sternal stability was maintained in 34 patients (92%). There were seven deaths (16%), of which two were considered to be wound-related. Median hospital stay of survivors was 34 (range 16-84) days. Comparison with 88 matched controls by univariate analysis showed preoperative chronic obstructive airways disease, reduced FEV1/FVC ratio (both P < 0.001) and smoking (P < 0.05) were all more common in the dehiscence group. In addition, reoperation for bleeding (P < 0.05), prolonged bypass time, postoperative ventilation period and length of stay in the intensive care unit (all P < 0.001) were more common in the study group.


'Fracture' of the penis in Enugu, Nigeria. Eight cases of 'fracture' of the penis in a Negro population over a 5-year period are presented. The majority of the cases occurred on the right side in association with sexual activity. All gave a positive history of sexually transmitted disease. We recommend prompt operative treatment that is aimed at full functional and cosmetic recovery.


Transcranial Doppler measurement before and after carotid endarterectomy. Carotid endarterectomy not only removes a source of emboli but significantly increases flow up the internal carotid artery (ICA). ICA flow and middle cerebral artery velocity (Vmca) measurements were made before, during and after endarterectomy in 40 consecutive patients. Mean ICA flow increased from 207 ml/min (95% confidence interval (CI) 136-259) to 388 ml/min (95% CI 348-428) (P < 0.001, Mann-Whitney U test) following endarterectomy. Despite this, Vmca did not rise significantly at the end of the procedure. By the first postoperative day Vmca rose to 55.3 cm/s (95% CI 47.6-62.4) (P < 0.025, ANOVA) only to fall preoperative values (46.0 cm/s (95% CI 40.0-52.1)) by 6 weeks. These results suggest that cerebral autoregulation takes time to adapt to the increased flow and pressure following endarterectomy, but has stabilized by 6 weeks.


Neopylorus: a functional reflux-free gastroenteral anastomosis. To minimize the loss of pyloric function associated with partial gastrectomy (PG), a functional surrogate pylorus, or neopylorus, was made by means of a pantaloon jejunoplastic pouch into which the gastrojejunal stoma was invaginated. This report concerns a consecutive series of 84 patients who underwent PG according to currently accepted criteria. The results showed that formation of the neopylorus apparently prevents dumping and may avoid the necessity for vagotomy in cases without serious hypersecretion. PG patients with a neopylorus formed over 13 years ago still exhibit no enterogastric reflux, gastritis, anaemia, steatorrhoea or sequelae of impaired digestion. Patient satisfaction has been most encouraging. Because this report is a feasibility trial only, no statistical analysis is presented.


Investigation of cervical lymphadenopathy presumed to be metastatic in nature: a review of current clinical practice. The method adopted by UK otolaryngologists for investigating cervical lymphadenopathy presumed to be metastatic in nature is reported. This is based on a confidential questionnaire sent to all members of the British Association of Otolaryngologists. The results of this survey show that the majority of otolaryngologists make a diligent search for a possible primary tumour by performing a panendoscopy. They do not, however, make full use of other investigative techniques such as fine needle aspiration cytology (9%) or computed tomography (6%). The management of patients with cervical masses could be improved by more widespread use of computed tomographic scanning where available and the development of fine needle aspiration cytology in all departments performing head and neck surgery.


Mondor's disease: analysis of 30 cases.

Mondor's disease: analysis of 30 cases. Thrombophlebitis of the superficial veins of the breast is a well known disease entity, the aetiology of which remains obscure. It affects mostly middle-aged women with large pendulous breasts. The present study suggests that the causative agent may not be a single factor but rather a combination of factors. Thirty cases (28 women, two men) are presented and analysed. A larger multicentre study is recommended.


Value of scintigraphic localization of obscure gastrointestinal bleeding. A total of 51 technetium-99m (99mTc)-labelled autologous red cell (LRC) scans performed on 49 patients for the localization of obscure gastrointestinal bleeding over a 5-year period was reviewed. The sensitivity for LRC scanning was 72.7% with a positive predictive value of 84.2%. Forty patients underwent both LRC scanning and visceral angiography during the same admission; angiography had a sensitivity of 38.9% compared with 66.7% for LRC scanning and the positive predictive values were 77.8% and 85.7%, respectively. Overall, the site of bleeding was located in 22 (45%) of 49 patients, but LRC scanning alone was successful in identifying the lesion in 16 (33%) cases. In patients who continue to bleed to the point of requiring operation, a combination of scintigraphy and angiography will localize a source in 70% of patients.


Acute epiglottitis in adults: a potentially lethal cause of sore throat. The diagnosis, management and outcome in 12 adults with acute epiglottitis was reviewed. Painful dysphagia was a universal symptom and respiratory distress affected eight patients, six of whom required urgent airway intervention. All patients received parenteral antibiotics, ten received steroids and four received adrenaline. Respiratory distress resolved in two patients given adrenaline and airway intervention was avoided. Indirect laryngoscopy is the investigation of choice and this is preferable to neck radiology. Two patients died and it is stressed that this condition must be distinguished from other more common causes of a severe sore throat. The patient should be managed in a unit with the facilities and expertise to effect acute airway intervention.


Surgical treatment of adult trigger finger under local anaesthetic: the method of choice? A prospective trial releasing 25 adult trigger fingers under a local anesthetic (5 ml 1% lignocaine with 1500 units hyalase) and a tourniquet was undertaken. All patients had excellent results and there was no complication. The adequacy of the release could be checked on the table by asking the patient to make a first actively, and any further measures necessary were carried out at the same time. It is recommended that the release of trigger fingers be carried out by this technique to minimize failures, as coexisting pathology causing two-level triggering can be identified and treated at the same time. The potential of complications is far less than with a general anaesthetic or a regional anaesthetic.


Potential anti-AIDS naphthalenesulfonic acid derivatives. Synthesis and inhibition of HIV-1 induced cytopathogenesis and HIV-1 and HIV-2 reverse transcriptase activities. Several naphthalenedi- and trisulfonic acids have been synthesized and evaluated for inhibitory potential against cytopathogenesis and purified recombinant human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) reverse transcriptase (RT). The most potent derivative that emerged from the anti-RT study was a small molecule 6 (MW = 840), a dipalmitoylated derivative of 2,7-naphthalenedisulfonic acid. Analog 6 demonstrated 50% inhibitory concentration (IC50) values of 2.42 and 0.86 microM for HIV-1 and HIV-2 RT, respectively. The second most active compound was also a derivative of the same naphthalenedisulfonic acid but contained only one palmitoyl moiety. This compound 9 displayed IC50 values of 4.8 and 3.7 microM for HIV-1 and HIV-2 RT, respectively. Both analogs 6 and 9 are active at noncytotoxic doses, exhibit slightly higher potencies for the RT of HIV-2 over HIV-1, and demonstrate activities superior to the hexasulfonic acid derivative suramin (IC50 values of 9.4 and 15.5 microM for HIV-1 and HIV-2 RT, respectively). In the cytopathogenesis assay, the most active compound is a bis naphthalenedisulfonic acid derivative 17, containing a flexible octamethylene spacer and exhibiting an in vitro therapeutic index of 29.7. Most striking, however, is the influence of the palmitoyl functionality in the naphthalenedisulfonic acid series to confer activity against both HIV-1 and HIV-2 RT.


Species differences in ciprofibrate induction of hepatic cytochrome P450 4A1 and peroxisome proliferation. Six species (CD-1 mouse, Fischer 344 rat, Syrian golden hamster, Duncan-Hartley guinea pig, half-lop rabbit and marmoset monkey) were treated orally with ciprofibrate, a potent oxyisobutyrate hypolipidaemic drug for 14 days. A dose-dependent liver enlargment was observed in the mouse and rat and at the high dose level in the hamster. A marked dose-dependent increase in the 12-hydroxylation of lauric acid was observed in the treated mouse, hamster, rat, and rabbit, associated with a concomitant elevation in the specific content of cytochrome P-450 4A1 apoprotein, determined by an ELISA technique. Similarly, in these responsive species, an increase in mRNA levels coding for cytochrome P450 4A1 was observed. Lauric acid 12-hydroxylation was unchanged in the guinea pig and marmoset after ciprofibrate pretreatment, and cytochrome P-450 4A1 was not detected immunochemically in liver microsomes from these latter species. In the untreated mouse, hamster, rat, and rabbit, the 12-hydroxylation of lauric acid was more extensive than the 11-hydroxylation, whereas in the guinea pig and marmoset the activity ratios were reversed, with 11-hydroxylation predominating. Peroxisomal fatty acid beta-oxidation was markedly induced in the mouse, hamster, rat, and rabbit on treatment at the higher dose level (39-, 3-, 13- and 5-fold, respectively) and was slightly increased in the marmoset (2-fold), yet was unchanged in the guinea pig following treatment.(ABSTRACT TRUNCATED AT 250 WORDS)


[Clinical significance of recombinant human granulocyte colony-stimulating factor (rG-CSF) in the chemotherapy of patients with malignant lymphoma]. We examined the effects of recombinant human granulocyte colony-stimulating factor (rG-CSF) on neutropenia induced by chemotherapy in 10 patients with non-Hodgkin's lymphoma (NHL). The numbers of peripheral blood hematopoietic progenitors were also evaluated before and after administration of rG-CSF. Six patients received an administration of 2 micrograms/kg/body weight of rG-CSF subcutaneously for 14 days after 2nd chemotherapy. Four patients received intravenous infusion of rG-CSF (300 micrograms/body/day) for 4 days from nadir state after chemotherapy. Administration of rG-CSF from the termination of chemotherapy, markedly shortend the period of bone marrow hypoplasia induced by chemotherapy. On the other hand, administration of rhG-CSF from nadir state after chemotherapy have accelerated the recovery of neutrophil counts. In addition, this type of therapy induced 26 to 60 folds increase of peripheral blood hematopoietic progenitors. These results demonstrate the validity of administration of rhG-CSF not only in the chemotherapy of NHL, but also in peripheral blood stem cell transplantation (PBSCT).


[Recombinant human granulocyte-colony stimulating factor (rhG-CSF) treatment for spleen abscess and periostitis in a patient with chronic granulomatous disease]. A 9-year-old boy with chronic granulomatous disease was hospitalized on May, 1991, because of continued fever and pain in the right elbow. Increased bone intensity at the distal end of right humerus on x-ray and a 33 x 36 mm space-occupying lesion in the spleen on abdominal CT scan were recognized. Under a diagnosis of periosteitis and spleen abscess, intravenous infusion of rhG-CSF at a dose of 200 micrograms/m2/day was started in combination with antimicrobial therapy. Fever, tenderness, swelling in the right elbow and inflammatory indices improved three weeks after the institution of therapy. Hydrogen peroxide (H2O2) formation by neutrophil increased significantly, although intermittently, during the therapy. The spleen abscess had completely vanished on CT scan on February, 1992. The therapy was well tolerated and no significant side effects were observed. The use of rhG-CSF in combination with potent antibiotics is recommended for patients with serious infections in chronic granulomatous disease to avoid a fatal course.


[Analysis of mononuclear cells in urine using flow cytometry: a useful tool for monitoring disease activity of proliferative glomerulonephritis]. We investigated CD56+ cells (natural killer cells), CD14+ cells (macrophage) and CD3+ cells (pan T cells) in urine using flow cytometry in various renal diseases including idiopathic crescentic glomerulonephritis, IgA nephropathy, membranoproliferative glomerulonephritis membranous nephropathy, pyelonephritis and idiopathic renal hematuria. A remarkable increase of CD56 cells in urine was observed in glomerulonephritis with marked necrotizing/and or crescentic (NC) lesions. The ratio of CD56+ cells/CD3+ cells was correlated with the severity of NC lesions. The ratio of CD14+ cells/CD3+ cells was increased in glomerulonephritis with endocapillary proliferation. Using immunohistochemical methods, CD56+ cells were also observed to be present in cellular crescents in biopsy specimens. These observations suggest that an analysis of these cells in urine using flow cytometry may be a useful tool for monitoring disease activity in proliferative glomerulonephritis.


Inhibitory action of tranilast, an anti-allergic drug, on the release of cytokines and PGE2 from human monocytes-macrophages. Tranilast, an anti-allergic drug that inhibits the release of substances such as histamine and prostaglandins from mast cells, has been reported to improve keloids and hypertrophic scars which originate from the abnormal proliferation and excessive collagen accumulation of fibroblasts. It has been considered that various chemical mediators produced by inflammatory cells play important roles in the development of keloids and hypertrophic scars. We therefore studied the effect of tranilast on the release of chemical mediators including transforming growth factor (TGF)-beta 1, interleukin (IL)-1 beta and prostaglandin (PG) E2 which are produced by the human monocytes-macrophages, and estimated whether these mediators induce collagen synthesis and cell proliferation of normal skin fibroblasts. Tranilast inhibited the release of TGF-beta 1, IL-1 beta and PGE2 from the human monocytes-macrophages. TGF-beta 1 (25-200 pM) enhanced the collagen synthesis by fibroblasts. IL-1 (0.1-1 U/ml) increased the proliferation and conversely decreased the collagen synthesis. PGE2 (2 micrograms/ml) enhanced the collagen synthesis. These results suggest that tranilast suppresses collagen synthesis by fibroblasts through inhibiting TGF-beta 1 and PGE2 production and cell proliferation by fibroblasts through inhibiting IL-1 production by inflammatory cells such as macrophages.


The mechanism involved in the inhibitory action of tranilast on collagen biosynthesis of keloid fibroblasts. Tranilast, an anti-allergic drug inhibiting the release of substances such as histamine and prostaglandins from mast cells, was previously reported to suppress collagen synthesis of fibroblasts derived from keloid tissues. However, the inhibitory mechanism on collagen synthesis is unknown. We studied its inhibitory mechanism on collagen synthesis by culturing fibroblasts from keloid and hypertrophic scar tissues of humans. Collagen synthesis of fibroblasts from keloid and hypertrophic scar tissue is greater than that from healthy human skin. Tranilast (3-100 microM) did not inhibit prolyl hydroxylase (the rate-limiting enzyme in collagen synthesis) activity. Tranilast (3-300 microM) suppressed the collagen synthesis of fibroblasts from keloid and hypertrophic scar tissue but not healthy skin fibroblasts. Tranilast (30-300 microM) inhibited the release of transforming growth factor (TGF)-beta 1 from keloid fibroblasts, which enhances the collagen synthesis of keloid fibroblasts. Anti-TGF-beta 1 antibody (50 microliter/ml) inhibited the collagen synthesis, although diphenhydramine (10 microM) and indomethacin (10 microM) did not show any inhibition. These results suggest that tranilast inhibits collagen synthesis of fibroblasts from keloid and hypertrophic scar tissue through suppressing the release of TGF-beta 1 from the fibroblasts themselves.


[Clinical significance of urinary flow pattern--based on combined uroflowmetry and external sphincter electromyography]. We performed combined uroflowmetry and external sphincter electromyography in 108 patients (87 males and 21 females); 16 serving as normal controls, 49 with benign prostatic hyperplasia, 16 with overactive type of neurogenic bladder, 27 with underactive type of neurogenic bladder. Urinary flow pattern was classified into 5 categories. All of urinary flow patterns of normal controls showed pattern A which had the form of a bell. EMG showed complete suppression during micturition followed by a few intermittent increases in amplitude. Urinary flow patterns of BPH patients were distributed widely from pattern A to E. Intermittent increases in EMG amplitude during a late phase of micturition were characteristic in patients with BPH. We must pay attention to sex differences to evaluate urinary flow pattern because it could be influenced by abdominal pressure such as stressing or Créde maneuver in female patients with an underactive type of neurogenic bladder.


[Production of polyclonal antibody against human androgen receptor and immunohistochemical study of human androgen receptor in prostatic tissues]. We produced polyclonal antibody against human androgen receptor (hAR) by means of immunizing a rabbit with hAR fusion protein that was expressed in E. coli. In Western blot analysis, this antibody, NH27, recognized two protein bands at the site of 110 kDa and 107 kDa in androgen-independent human prostatic cancer cells (PC-3), transfected with full-length hAR expression plasmid DNA and at the site of 114 kDa and 108 kDa in androgen-dependent human prostatic cancer cells (LNCaP). In immunohistochemical examination with NH27, the nuclei of epithelial and stromal cells in human benign prostatic hyperplasia were mainly stained as did with AN1-15, commercially available hAR monoclonal antibody. Titer of NH27, however, was about five times more high than that of AN1-15. In prostatic cancer cells the nuclei were stained with NH27 as did with AN1-15. Intensity of staining was various between the nuclei of cancer cells. The polyclonal antibody, NH27, produced in the present study is useful in investigating the characterization of AR in androgen-dependent and -independent prostatic cancers.


[Evaluation of renal function and prediction of renal functional recovery in children with unilateral hydronephrosis using renal pelvic urine]. In 29 children with unilateral hydronephrosis who underwent surgery at the age from 2 months to 15 years (27 patients with ureteropelvic junction stenosis and 2 with obstructive megaureter), beta 2-microglobulin (beta 2-MG), alpha 1-microglobulin (alpha 1-MG), N-acetyl-beta-D-glucosaminidase (NAG) and albumin were determined in renal pelvic urine from the hydronephrotic kidney to evaluate renal dysfunction accompanying urinary tract obstruction. Moreover, it was also examined whether it is possible to predict functional recovery of the hydronephrotic kidney on the basis of relation between these indices and pre- and postoperative changes in renal dimercaptosuccinic acid (DMSA) uptake rate. The values of beta 2-MG, alpha 1-MG, NAG and albumin in urine from the renal pelvis were high in 48%, 50%, 75% and 83% of the patients, respectively. Among the patients of one year and up, those with low preoperative DMSA uptake rate tended to have high values of beta 2-MG, alpha 1-MG and NAG. On the contrary, albumin level was high in 78% of patients who had good preoperative DMSA uptake rate. With respect to the relation between pre- and postoperative changes in DMSA uptake rate and each index, beta 2-MG and alpha 1-MG were high in 73% and 62% of patients who exhibited a marked increase in postoperative DMSA uptake rate. In patients without a remarkable change in DMSA uptake rate before and after surgery, on the other hand, the values of these were high only in 25% and 36%.(ABSTRACT TRUNCATED AT 250 WORDS)


[Prostate cancer after subcapsular prostatectomy diagnosed as benign prostate hypertrophy--clinico-pathological analysis]. Of 160 newly diagnosed cases of prostate cancer during last 11 years, six (3.75%) had a prior subcapsular prostatectomy. Digital rectal examination in these six cases revealed a significant prostatic abnormality and multiple bone metastases were showed. Histological examination by step-section technique was done retrospectively using surgical materials from subcapsular prostatectomy. Two cases of incidental carcinoma were detected histologically. One showed stage A1 and another stage A2. Continuous observation should be performed after prostatectomy, even if the surgical specimens revealed no carcinoma.


Production and epidemiological application of monoclonal antibody specific for Salmonella O5-antigen. Salmonella typhimurium is an important causative agent of acute gastroenteritis (food poisoning), and the decision of the source of infection urgently requires epidemiological investigation. There are two types of S. typhimurium, O5-antigen-carrier type (O5(+)-antigen type) and noncarrier type (Copenhagen antigen type). On the assumption that serological differentiation of the types is effective for epidemiological exploration for the source of infection, we produced a monoclonal antibody, TMY1, specific for the O5-antigen. We classified S. typhimurium identified as the causative agent of mass outbreaks of acute Salmonella gastroenteritis according to the O5-antigen type, by using the TMY1. As a result, the bacterium in each outbreak was classified as the O5(+)-antigen type or the Copenhagen antigen type based on the difference in reactivity with TMY1. S. typhimurium isolated from calves in mass outbreaks of diarrhea and from animals with various diseases were also classified by TMY1 according to the O5-antigen type, and TMY1 was found to be as useful as in human cases. From this confirmation, TMY1 was demonstrated to be useful as a marker for epidemiological investigation of the source of infection by the O5-antigen type of S. typhimurium.


Naftopidil, a new adrenoceptor blocking agent with Ca(2+)-antagonistic properties: interaction with adrenoceptors. The interaction of naftopidil with adrenoceptors was studied in comparison to standard drugs. Naftopidil binds specifically to alpha 1-adrenoceptors. The Ki values are 58.3 nM for naftopidil, 0.43 nM for prazosin, and 197 nM for urapidil. The affinities of naftopidil to alpha 2- and beta-adrenoceptor sites are very low (> 6,000 and > 2,500 nM). Naftopidil relaxes aortic strips precontracted with norepinephrine concentration-dependently, and it shifts the concentration-response curve of norepinephrine in a parallel manner to the right. The pA2 values are 7.10 for naftopidil, 8.85 for prazosin, and 6.25 for urapidil. In pithed rats, naftopidil shifted the dose-response curve of methoxamine at equipotent hypotensive doses to the same extent to the right as does prazosin, but both drugs barely affected (in contrast to phentolamine) the response to norepinephrine. In concentrations that are about 10 times higher than those required for alpha 1-adrenoceptor blockade, naftopidil relaxes (in contrast to prazosin) aortic strips depolarized with K+, and it shifts Ca2+ concentration-response curves to the right (pA2 value of 5.90), thus suggesting Ca(2+)-channel-blocking activity. Both alpha-adrenoceptor and Ca(2+)-blocking activities are exerted to nearly the same extent by both stereoisomers. Naftipidil does not affect the response to isoprenaline-induced effects, indicating that the compound does not possess beta-blocking properties.


Effects of the selective neutral endopeptidase inhibitor, retrothiorphan, on renal function and blood pressure in conscious normotensive Wistar and hypertensive DOCA-salt rats. Atrial natriuretic peptide (ANP) is degraded by neutral endopeptidase (NEP) mainly in the proximal tubule of the kidneys. We studied the effects of retrothiorphan, a potent and highly specific NEP inhibitor on renal function and blood pressure (BP). A 25-mg/kg bolus injection (group bolus), or bolus injection plus infusion 25 mg/kg + 25 mg/kg/h (group infusion), was given to conscious normotensive Wistar and hypertensive DOCA-salt rats. Bolus and infusion produced increases in diuresis (110 +/- 15 vs. 103 +/- 15 vs. 42 +/- 9 microliters/min) and natriuresis (10.6 +/- 3.0 vs. 7.0 +/- 1.0 vs. 5.4 +/- 1.0 mumol/min) in normotensive rats, with a maximum change at 30 min. Change in kaliuresis was not significant. These renal effects were associated with nonsignificant increases in urinary cyclic GMP and ANP. Arterial pressure and heart rate (HR) were not affected. Bolus or infusion of retrothiorphan also induced increases in diuresis (92 +/- 16 vs. 124 +/- 13 vs. 38 +/- 6 microliters/min) and natriuresis (10.3 +/- 2.0 vs. 12.5 +/- 1.0 vs. 5.0 +/- 1.0 mumol/min) in DOCA-salt hypertensive rats, with a maximum change at 30 min. The changes in diuresis and natriuresis induced by retrothiorphan were correlated with a significant increase in urinary cyclic GMP excretion (r = 0.89, p < 0.001 and r = 0.91, p < 0.001). Urinary ANP did not change in controls but significantly increased in the treated rats; urinary immunoreactive bradykinin (BK) also tended to increase. Plasma ANP and hematocrit did not change after retrothiorphan, but plasma cyclic GMP increased significantly after infusion. Only infusion caused a decrease in arterial pressure in DOCA-salt rats (-20 mm Hg at 120 min). Renal clearance studies in DOCA-salt rats showed that retrothiorphan has a transient effect on renal hemodynamics, with increases in glomerular filtration and renal blood flow (RBF) and a decrease in renal vascular resistance (RVR). Its renal action was also tubular, with an increase in fractional sodium excretion. We also compared the effects of retrothiorphan in normotensive Brown-Norway kininogen-deficient rats (BN-Kat) and DOCA-salt hypertensive kininogen-deficient rats. The NEP inhibitor induced increases in diuresis and natriuresis in both groups, with increased urinary cyclic GMP. Urinary immunoreactive BK did not change significantly in normotensive or DOCA-salt hypertensive kininogen-deficient rats.(ABSTRACT TRUNCATED AT 400 WORDS)


[Spiro-ergometric studies after corrective surgery of tetralogy of Fallot]. Treadmill exercise electrocardiography and spirometry was recorded in 61 patients (aged from 5 to 23 years) who underwent corrective surgery for tetralogy of Fallot. The Bruce-protocol and a modified interval-protocol were compared to find out their ability to induce arrhythmias. Supraventricular arrhythmias were predominantly provoked by the interval-protocol while maximal exhaustion is often necessary for inducing ventricular arrhythmias which we found in 23% of our patients. Most of them were seen in the periods of recovery between or after the exercise. We propose a combination of both protocols, which will be compared with established forms of exercise-testing in further studies. The results of rhythm analysis of consecutive exercise tests in one patient after surgical repair could possibly be compared by using an "arrhythmia score" which tries to indicate the severity of different forms of arrhythmias. The values of maximal heart rate, oxygen consumption and endurance time recorded at maximal exercise (Bruce-protocol) were about 15% lower than correspondent values of healthy persons found by other authors.


Arterial and antihypertensive effects of nitrendipine: a double-blind comparison versus placebo. Arterial effects evaluated by carotid-femoral, brachial-radial, and femoral-tibial pulse wave velocity and antihypertensive effect evaluated by 24-h ambulatory blood pressure (BP) monitoring were measured in 17 hypertensive patients before and 24 h after once-daily nitrendipine (20 mg) administration. After a 15-day placebo period, a double-blind study of nitrendipine versus placebo was performed for 1 month. After nitrendipine dosing, BP measured by sphygmomanometer 24 h after the last drug intake showed a significant decrease as compared with the pretreatment period. Ambulatory BP mean values were also significantly decreased for systolic and diastolic BP (SBP, DBP). This decrease predominated during the day but was observed nocturnally only after 6 a.m. Twenty-four hours after the last tablet intake of nitrendipine, carotid-femoral and brachial-radial pulse wave velocities were significantly reduced, whereas femoral-tibial wave velocity was unchanged, indicating that markers of arterial rigidity might be substantially modified and that the modifications were partly unrelated to BP changes. The results provide evidence that in hypertensive subjects nitrendipine 20 mg given once daily for 1 month produces an arterial effect for 24 h, in association with BP reduction.


Effects of nifedipine and diltiazem on myocardial ischemia in patients with severe stable angina pectoris treated with nitrates and beta-blockers. In a randomized, cross-over, double-blind study, the effects of nifedipine were compared with those of diltiazem in 20 patients with severe stable angina pectoris and multivessel coronary artery disease treated with nitrates and beta-blockers. The comparison was performed by bicycle ergometry, clinical evaluation, and ambulatory 24-h ECG monitoring for 7-8 weeks. As compared with placebo, both nifedipine and diltiazem significantly reduced the daily number of anginal attacks and nitroglycerin consumption; prolonged exercise duration, time to 1-mm ST segment depression, and to onset of angina; and reduced the sum of ST segment depressions at maximal identical load in ergometry. In ambulatory ECG monitoring, only nifedipine significantly diminished the duration of asymptomatic ST segment depression as compared with placebo. Antianginal and antiischemic effects of nifedipine and diltiazem were similar. Both nifedipine and diltiazem significantly increased the effects of treatment with nitrates and beta-blockers. Administration of nifedipine was safer because at night diltiazem caused significant bradycardia despite careful titration of optimum doses of the drug. Although the maximum well-tolerated doses of conventional medication suppressed anginal symptoms in some patients, they did not abolish ischemia either at ergometry or in daily life.


Effects of pirenzepine and hexamethonium on adrenal catecholamine release in responses to endogenous and exogenous acetylcholine in anesthetized dogs. We investigated the way in which hexamethonium and pirenzepine, a selective muscarinic (M) 1 receptor antagonist, modify the release of catecholamines from dog adrenal gland in response to endogenous and exogenous acetylcholine (ACh) in vivo. Output of epinephrine (EPI), and norepinephrine (NE) was determined from adrenal venous blood by high-performance liquid chromatography (HPLC) with electrochemical detection. Intraarterial (i.a.) injections of ACh (1.5 and 3 micrograms) or muscarine (3 and 6 micrograms) into the phrenicoabdominal artery and splanchnic nerve stimulation (SNS, 3 Hz) produced marked increases in EPI and NE output. Hexamethonium (1 mg/kg intravenously, i.v.) inhibited the increases in EPI and NE output in response to exogenous ACh and SNS. Pirenzepine (10 micrograms/kg i.v.) inhibited the ACh-induced increases in EPI and NE output but did not modify the SNS-induced increases. The muscarine-induced increases in EPI and NE output were also inhibited by pirenzepine. These results indicate that the exogenous ACh-induced release of adrenal catecholamines is mediated through both nicotinic and M1 receptors, in contrast to the predominant mediation of nicotinic receptors in response to endogenous ACh.


Neurohormonal and blood pressure responses to low-dose infusion of an orally active renin inhibitor, Ro 42-5892, in salt-replete men. Renin inhibitors are an alternative means of blockade of circulating and tissue-based renin-angiotensin systems (RAS). We studied a new renin inhibitor, Ro 42-5892, by low-dose (0.1 mg/kg) intravenous (i.v.) infusion in 10 min (fast) or 6 h (slow) or placebo in a double-blind cross-over study to assess the relationship between drug concentration and response. Fasting salt-replete normotensive male volunteers (n = 9) aged 18-32 years were studied supine. There were no significant changes in blood pressure (BP) or heart rate (HR) between drug and placebo infusion. Drug concentration peaked (482 +/- 140 ng/ml) at the end of the fast infusion or showed a sustained plateau (25.9 +/- 6.1 ng/ml) with the slow infusion (mean time to peak 121 +/- 99 min). Both fast (135.2 +/- 26 ng/ml/h2) and slow (121.0 +/- 31.1 ng/ml/h2) infusions had similar area under the curve (AUC)0-24-values. Plasma renin activity (PRA) was dramatically reduced by both strategies, but AUC0-10 for PRA was significantly less for slow (1.7 +/- 0.6 ngAI/ml/h2) than fast (4.9 +/- 2.5 ngAI/ml/h2) infusions. Mean peak plasma active renin (AR) concentration was increased by both fast (102.2 +/- 65.9 pg/ml) and slow (195.2 +/- 110.5 pg/ml) infusions as compared with placebo (49.9 +/- 18.6 pg/ml). Similarly, AUC0-10 for AR was greater for slow (990.2 +/- 582.1 pg/ml/h) than fast (512.4 +/- 189.4 pg/ml/h) infusions. Plasma angiotensin-converting enzyme (ACE) activity was unaltered. Our results indicate that protracted low concentrations of Ro 42-5892 may provide more effective and long-lasting inhibition of renin.(ABSTRACT TRUNCATED AT 250 WORDS)


Postjunctional alpha-adrenergic stimulation of inotropy in hypoperfused myocardium outside an acute infarct. The functional significance of myocardial postjunctional alpha-adrenergic support of inotropy in the vicinity of an acute regional ischemic zone was addressed in pentobarbital-anesthetized, beta-adrenergic blocked cats with circumflex coronary artery occlusion. Regional myocardial performance was measured by ultrasonic crystals in the anterior wall perfused by the left anterior descending coronary artery (LAD) before and during postjunctional alpha-adrenergic antagonism (SK&F 104078 2 mg/kg). A group with unrestricted flow in the LAD (control group) was compared with a group perfused below the autoregulatory pressure range (stenosis group). End-systolic pressure-length relations during dynamic after-load elevation were calculated for assessment of regional contractility. Regional myocardial blood flow (RMBF) was measured by radioactive microspheres. SK&F 104078 did not alter regional myocardial shortening or the slope of end-systolic pressure-length relations in the control group. In the stenosis group, however, alpha-adrenergic antagonism produced significant deterioration of shortening as well as consistent reduction of the slope of the end-systolic pressure-length relations (p < 0.05). As a reflection of reduced demands for perfusion, impairment of midmyocardial and endocardial blood flow occurred in the stenosis group (p < 0.05). These findings imply a negative inotropic effect of SK&F 104078 in metabolically vasodilated myocardium in the vicinity of an acute ischemic region.


Electromechanical action of dofetilide and D-sotalol during simulated metabolic acidosis in isolated guinea pig ventricular muscle. We examined the electromechanical effects of two class III antiarrhythmic agents, dofetilide (UK-68,798) and D-sotalol, in acidic myocardium. Right ventricular papillary muscle preparations isolated from guinea pigs were divided into three groups (n = 6 per group): (a) drug-free, (b) dofetilide (10 nM), and (c) D-sotalol (30 microM). At normal extracellular pH (pH = 7.32 +/- 0.01), dofetilide and D-sotalol lengthened action potential duration (APD) to a similar extent, i.e., by 18-20%. Effective refractory period (ERP) increased in parallel, whereas membrane diastolic potential (MDP), action potential amplitude (APA), maximum velocity of depolarization (Vmax), and developed force (DF) were not significantly affected. Metabolic acidosis (pH = 6.78 +/- 0.01) was simulated by reducing the bicarbonate concentration of the Tyrode's solution from 20 to 6 mM. Superfusion with acidic solution alone for 30 min markedly decreased Vmax and DF, whereas APD and ERP were lengthened slightly. The acidosis-induced decreases in Vmax and DF were not affected by pretreatment with dofetilide or D-sotalol. In acidic superfusate, both agents still significantly increased APD and ERP to the same extent that they did at normal pH. The results indicate that metabolic acidosis, a major component of myocardial ischemia, does not attenuate the class III antiarrhythmic action of dofetilide and D-sotalol.


Effects of manidipine hydrochloride on the renal microcirculation in spontaneously hypertensive rats. We wished to clarify the effects of a newly developed calcium antagonist, manidipine hydrochloride (HCl), on renal microcirculation in hypertensive rats by using the micropuncture technique. Oral administration of manidipine HCl for 2 months reduced systemic blood pressure (BP), did not change the single-nephron glomerular filtration rate (SNGFR), but increased the SNG plasma flow (SNGPF). Moreover, the glomerular transcapillary hydraulic pressure difference (delta P), which is assumed to be the parameter most related to development of glomerulosclerosis, was significantly reduced. Both afferent and efferent arteriolar resistance (RA and RE) were reduced. Intravenous (i.v.) infusion of manidipine HCl (20 micrograms/kg) decreased systemic BP but did not change SNGFR, SNGPF, or delta P. Both RA and RE were also significantly decreased. These results indicate that chronic administration of manidipine HCl increases renal blood flow (RBF) by dilating the afferent arterioles and improves glomerular hypertension by dilating the efferent arterioles. Thus, manidipine HCl might be a beneficial antihypertensive agent for patients with renal diseases. Because acute i.v. infusion of manidipine HCl did not change delta P, apparently time must elapse before glomerular hypertension is corrected.


Effect of cilostazol, a cyclic AMP phosphodiesterase inhibitor, on the proliferation of rat aortic smooth muscle cells in culture. Cilostazol, a cyclic AMP phosphodiesterase inhibitor, has been used as an antiplatelet agent. In the present study, we investigated the in vitro effect of cilostazol on DNA synthesis in rat aortic arterial smooth muscle cells (SMCs) in culture stimulated with fetal calf serum (FCS), platelet-derived growth factor (PDGF), insulin, or insulin-like growth factor-I (IGF-I). Micromolar concentrations of cilostazol inhibited [3H]thymidine incorporation into DNA and cell growth as determined by cell number and protein concentration. Treatment with cilostazol increased the intracellular concentration of cyclic AMP, suggesting that the inhibition of SMC proliferation by cilostazol may be mediated through increased levels of cyclic AMP. The results suggested that cilostazol, by interfering with the proliferation of arterial SMCs, may have potential to prevent initiation and progression of atherosclerosis.


Desensitization of nitrate-induced venodilation: reversal with oral N-acetylcysteine in humans. The objective of this study was to determine whether the dorsal hand vein could be used as a model to study tolerance to oral nitrates, and whether oral N-acetylcysteine (NAC) could reverse tolerance if present. Dose-response curves to nitroglycerin were constructed for 11 normotensive volunteers before and during treatment with a sustained-release formulation of isosorbide dinitrate, 80 mg, three times daily for 7 days and followed by concurrent treatment with NAC at a mean dose of 150 mg/kg/day, in divided doses, for 2 days. In separate studies, dose-response curves were constructed for seven normotensive volunteers before and after treatment with oral NAC at the same dose for 2 days. Nitroglycerin's Emax was significantly attenuated from 115 +/- 36 to 77 +/- 22% after treatment with isosorbide dinitrate alone (p < 0.009). Concurrent treatment with NAC reversed this decrease, as nitroglycerin's Emax of 108 +/- 26% during coadministration of isosorbide dinitrate and NAC was not different from its Emax in the control period. There was also no difference in the dose of phenylephrine required to cause 80% of maximal venoconstriction throughout the study. These studies demonstrate that smooth muscle tolerance to nitrates can be demonstrated in medium-sized veins in humans. In addition, high-dose oral NAC can reverse existing tolerance to oral nitrates in human veins. These results indicate that the dorsal hand vein compliance technique is a good model for the clinical investigation of tolerance to nitrates in humans.


Effects of WAY-123,398, a new class III antiarrhythmic agent, on cardiac refractoriness and ventricular fibrillation threshold in anesthetized dogs: a comparison with UK-68798, E-4031, and dl-sotalol. Previous studies in isolated ventricular myocytes showed that WAY-123,398 is a selective blocker of the delayed rectifier K+ current (IK). In this report, we studied the electrophysiological and hemodynamic effects of WAY-123,398 in open-chest anesthetized dogs. WAY-123,398 prolonged atrial and ventricular refractoriness without affecting conduction; WAY-123,398 was as effective as UK-68798, E-4031, and dl-sotalol, but less potent than UK-68798 and E-4031. The increase in atrial refractoriness was approximately twice as large as the ventricular increase with all compounds. The hemodynamic effects of WAY-123,398 were similar to those of UK-68798; at the ED20 for increasing ventricular refractoriness, WAY-123,398 did not affect the mean arterial pressure and decreased the heart rate by 20%. In a different series of experiments, all four compounds produced large and comparable increases in the ventricular fibrillation threshold in anesthetized dogs; WAY-123,398 and UK-68798 induced defibrillation and restoration of sinus rhythm in two of six dogs each and E-4031 in one of six dogs. No episodes of drug-induced restoration to sinus rhythm were observed in dogs treated with sotalol or vehicle. In conclusion, WAY-123,398 is an effective Class III agent without Class I actions and with a favorable hemodynamic profile.


Differences in responses to TC-81 among various arteries in dogs. The vasodilation induced by TC-81 was investigated in vitro and in vivo. In helical strips of dog arteries precontracted with 65.4 mM KCl, TC-81, nicardipine, nifedipine, diltiazem, and papaverine produced concentration-dependent relaxation. The potencies of TC-81 were in the following order: basilar > coronary > femoral > renal > mesenteric arteries. The other drugs also showed a similar property of greater response in basilar and coronary arteries than in renal and mesenteric arteries. However, the difference in reactivity to TC-81 was greater. On the other hand, TC-81, nicardipine, and papaverine dose-dependently increased the blood flow in vertebral, coronary, and femoral arteries in anesthetized dogs. However, the blood flow in renal and mesenteric arteries was not changed or decreased. The decreases in vessel resistance induced by TC-81 were in the following order: vertebral > coronary > femoral > renal = mesenteric arteries, agreeing with the experimental results in vitro. These results suggest that Ca2+ antagonists have the pharmacological property of vasodilating cerebral and heart blood vessels more selectively than other arteries, and this property of TC-81 might be an advantage compared with other drugs.


Defibrillation energy requirements during moricizine and moricizine-lidocaine therapy. Defibrillation energy requirements may be altered by antiarrhythmic agents. We investigated the effects of moricizine on the defibrillation threshold (DFT) in 18 pentobarbital-anesthetized pigs. The animals were randomized, in a blinded fashion, to moricizine or control (0.9% saline) treatment groups. Each group underwent three treatment phases: baseline, drug infusion (moricizine or saline), and drug infusion combined with lidocaine. Moricizine (2 mg/kg loading dose, 1.5 mg/kg/h infusion) and lidocaine (5 mg/kg loading dose, 4 mg/kg/h infusion) were dosed to achieve therapeutic concentrations. After 5 s of induced ventricular fibrillation, defibrillation was performed using a cardiac defibrillator interfaced with two epicardial electrode patches. DFTs were determined at baseline, during the drug phase, and during the combination of lidocaine with moricizine or saline. DFT values in the animals randomized to the control group were 15.2 +/- 4.2, 14.0 +/- 3.3, and 17.8 +/- 8.7 J at baseline, saline infusion, and saline combined with lidocaine, respectively. No significant differences were observed among the treatment phases. DFT values in the animals randomized to moricizine group were 12.1 +/- 2.8, 13.8 +/- 5.2, and 22.9 +/- 7.1 J at baseline, moricizine infusion, and moricizine combined with lidocaine, respectively. The DFT values during the lidocaine-moricizine combination treatment phase were significantly greater than baseline and moricizine alone (p < 0.002). The mean change in the DFT from baseline to moricizine (14% increase) was significantly different than the mean change in the DFT from baseline to saline (8% decrease) (p = 0.03). Lidocaine added to moricizine increased the DFT by 84%, which was significantly different from the 27% increase in the DFT when lidocaine was added to saline (p = 0.02). We conclude that moricizine minimally increases the DFT, but the combination of moricizine with lidocaine results in a synergistic rise in the DFT that may have detrimental clinical implications.


Pharmacologic characterization of an endothelinA (ETA) receptor antagonist in conscious rats. The present experiments describe the endothelin-1 (ET-1) antagonist activity of BQ123 (cyclic D-Asp-L-Pro-D-Val-L-Leu-D-Trp) in conscious Sprague-Dawley (SD) rats, and we also examined the effect blockade of ETA receptors had on blood pressure in four experimental models of hypertension. Rats were anesthetized with methoxyflurane and instrumented with femoral arterial and venous catheters. In SD rats, BQ123 (0.1-10.0 mg/kg i.v.) administered 5 or 60 min prior to ET-1 inhibited both the magnitude and duration of the ET-1 (0.25 nmol/kg i.v.) pressor response. In addition, BQ123 (10.0 mg/kg) inhibited the pressor response evoked by administration of the ET-1 precursor, proendothelin-1 (1.0 nmol/kg). However, BQ123 (10.0 mg/kg) had no effect on the pressor response evoked by ET-3 (0.75 nmol/kg). In Wistar-Kyoto rats, BQ123 (10.0 mg/kg) reversed the hypertension produced by an infusion of ET-1 (0.01 nmol/kg/min). Administration of BQ123 produced a mild antihypertensive effect in normal- to low-renin models of hypertension, but no blood pressure lowering was observed in high-renin models of hypertension. These studies demonstrated the selectivity of the ETA receptor antagonist, BQ123 for ET-1, but not ET-3-induced pressor responses. Furthermore, ET-1 does not appear to be a major contributing factor to the maintenance of elevated levels of blood pressure in four experimental models of hypertension.


Endothelium-dependent vasodilation is augmented by angiotensin converting enzyme inhibitors in healthy volunteers. We have examined the effects of local intra-arterial infusion of enalaprilat (an angiotensin converting enzyme inhibitor) on responses initiated by concomitantly infused acetylcholine (an endothelium-dependent vasodilator) and sodium nitroprusside (a direct dilator of smooth muscle) in the forearm arterial beds of healthy volunteers. Although the angiotensin converting enzyme inhibitor alone did not affect basal forearm blood flow or vascular resistance, it significantly augmented the increase in blood flow and reduction in vascular resistance induced by acetylcholine (both p < 0.05). Coinfusion of enalaprilat did not enhance sodium nitroprusside-induced vasodilation. Pretreatment with NG-monomethyl-L-arginine blocked the augmentation of blood flow induced by the angiotensin converting enzyme inhibitor. The effect of enalaprilat was still observed after the administration of acetylsalicylic acid (p < 0.05). These results suggest that angiotensin converting enzyme inhibitors potentiate nonprostanoid endothelium-derived relaxing factor in normal human forearm vasculature.


Electrophysiologic effects of RS-2135, a new antiarrhythmic compound, on canine Purkinje fibers. RS-2135 is the (+) isomer of a novel, fused carbazol derivative. The agent, when administered orally, shows long-lasting antiarrhythmic effects in several models of arrhythmia. We used standard microelectrode techniques to characterize the electrophysiological effects of the agent on canine Purkinje fibers. RS-2135 reduced the maximum upstroke velocity of the action potential (Vmax) and shortened the action potential duration (APD) in a concentration-related manner (0.3-3 microM). RS-2135 decreased Vmax at lower concentrations than disopyramide, flecainide, and mexiletine. RS-2135 shortened the effective refractory period (ERP), but significantly increased the ratio of ERP to APD90. Additionally, the effects of the (-) optical isomer of RS-2135 were compared with those of RS-2135, the (+) enantiomer. The (-) isomer was much less potent than RS-2135 in decreasing Vmax. These data suggest that RS-2135 belongs to the class I or "local anesthetic" type of antiarrhythmic agent and that the stereochemistry of the drug molecule is an important determinant of Na channel blocking activity.


Cardiac microdialysis measurement of extracellular adenine nucleotide breakdown products during regional ischemia and reperfusion in canine heart: protective effect of propranolol against reperfusion injury. Using cardiac microdialysis, we studied release of the adenine nucleotide breakdown products (ANBP) adenosine (ADS), inosine (INS), and hypoxanthine (HYP) into the interstitium of canine myocardium during 20- and 40-min occlusion of the anterior descending coronary artery and reperfusion. Dialysate ANBP concentrations reached maximum values not at the end of ischemia but in the first 10 min of reperfusion. The effect was more pronounced after 20-min ischemia. Further reperfusion led to an ANBP decrease that was more prolonged after 40-min ischemia. Pretreatment with DL-propranolol (0.5 mg/kg, intravenously, i.v.) given 40 min before coronary occlusion had no effect on adenine nucleotide catabolism rate during 20- and 40-min ischemia, but it facilitated washout of ANBP from ischemic zone immediately after the start of reperfusion. A similar effect was elicited by a D-stereoisomer of propranolol with no beta-adrenoceptor blocking activity. Results suggest that the reperfusion injury and probably the no-reflow phenomenon were the cause of enhanced adenine nucleotide catabolism at the beginning of reperfusion and prolonged ANBP washout from the ischemic zone. Reduction of reperfusion injury by propranolol could be related to the membrane stabilizing and antioxidant activity of this agent. Examination of DL-propranolol kinetics in arterial and coronary venous blood plasma showed that drug accumulation in the myocardium was almost maximum at the start of ischemia; therefore, the efficiency of cardio-protection with DL-propranolol was not limited by pharmacokinetic causes. Insertion of an additional microdialysis probe in the myocardium allowed monitoring of extracellular propranolol concentrations.


Effect of cloricromene during ischemia and reperfusion of rabbit hindlimb: evidence for an involvement of leukocytes in reperfusion-mediated tissue and vascular injury. The involvement of polymorphonuclear leukocytes (PMN) in reperfusion-mediated vascular injury was studied in a model of ischemia and reperfusion in rabbit hindlimb. Ischemia was induced by 4-h occlusion of the left iliac artery followed by 4-h reperfusion. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) activities, hindlimb vascular resistance (HVR), and myeloperoxidase (MPO) activity in the postischemic extensor digitorum longus (EDL) muscle were measured to evaluate the extent of vascular and skeletal muscle injury. In addition, the ischemia/reperfusion-induced injury of the hindlimb vasculature was evaluated by electron microscopy. Ischemia and reperfusion (n = 10) was associated with an increase in CK (6,380 +/- 1,346 U/L, p < 0.05) and LDH (552 +/- 76 U/L, p < 0.05) activities which were significantly greater than those observed in sham-operated control animals (CK 1,651 +/- 207 U/L, LDH 246 +/- 14 U/L; n = 6). HVR in sham-operated animals decreased by 20 +/- 3%, but increased in the ischaemic group by 56 +/- 16% (p < 0.05). MPO activity of EDL muscle increased from 7.3 +/- 3.9 U per muscle (sham) to 28.0 +/- 5.9 U per muscle (p < 0.05) after ischemia and reperfusion. Morphologic analysis did not show any alteration in the microvascular bed of the hindlimb. Moreover, 1 mg/kg/h intravenous (i.v.) cloricromene, an antithrombotic drug that inhibits superoxide anion production as well as PMN adhesion to endothelium, reduced the increase in plasma CK and LDH and the increase in MPO and HVR observed in animals subjected to hindlimb ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)


Differential effect of selective beta 1 and nonselective beta-adrenoceptor blockade on epinephrine and atropine response in normal humans. Sympathetic stimulation with epinephrine (EPI) combined with parasympathetic blockade with atropine was studied in 10 healthy volunteers premedicated with placebo or three different beta-adrenoceptor blockers: atenolol (62.5 micrograms/kg, beta 1-selective), propranolol (62.5 micrograms/kg, nonselective), and pindolol (7.5 micrograms/kg, nonselective with intrinsic sympathomimetic activity, ISA). EPI infusion (0.06 microgram/kg/min) after placebo increased heart rate (HR) and systolic blood pressure (SBP) and decreased diastolic BP (DBP). Pretreatment with atenolol reduced the HR increase, and caused similar changes in BP. In contrast, pretreatment with propranolol and pindolol decreased HR and increased BP. Combined EPI and atropine (15 micrograms/kg) after placebo increased HR by 40% without causing BP changes. Similar HR changes were observed after administration of all beta-adrenoceptor blockers, but whereas a marked pressor response was observed after propranolol and pindolol a blunted response was observed after atenolol. Propranolol and pindolol reduced myocardial oxygen demand estimated by the HR x BP product after EPI, but this response was abolished by atropine. Serum potassium decreased from 3.9 +/- 0.2 to 3.2 +/- 0.3 mM after EPi and atropine. This effect was less after atenolol, and potassium increased after premedication with propranolol and pindolol. Our results show that nonselective beta-adrenoceptor blockade has a favorable effect on potassium homeostasis and oxygen demand parameters during EPI infusion but causes a marked pressor response, contrary to a beta 1-selective agent, during combined sympathetic stimulation and parasympathetic blockade. They also highlight the importance of the vasodilator cholinergic system as a defense mechanism in such situations.


Prolonged activation of alpha 1 adrenoceptors induces down-regulation of protein kinase C in vascular smooth muscle. Sustained exposure of vascular smooth muscle to catecholamines results in desensitization of alpha 1-adrenoreceptor-mediated vascular smooth muscle contraction. The present study was designed to determine the effects of prolonged exposure of blood vessels to catecholamines on protein kinase C (PKC) activity. Incubation of rat aortic smooth muscle with 10 microM norepinephrine (NE) for 4 h resulted in a threefold decrease in sensitivity of the contractile response of rat aortic smooth muscle to the phorbol ester 4 beta-phorbol 12,13-dibutyrate (PDBu); this loss in sensitivity was dependent on the presence of endothelium. NE induced a 45% decrease in enzymatic activity of the soluble and particulate forms of PKC. With [3H]PDBu used to label phorbol ester receptor binding sites in the aorta, there was a 34% decrease in [3H]PDBu binding sites in NE-treated blood vessels without change in binding affinity for the ligand. To determine whether this loss in enzymatic activity and [3H]PDBu binding resulted from a decrease in the quantity of the enzyme, Western blot analyses were performed using a monoclonal antibody (MoAb) against PKC. This approach confirmed the presence of an 80-Kd immunoreactive PKC in the soluble fraction of rat aortic smooth muscle and demonstrated a 44% decrease in the amount of PKC in blood vessels after sustained exposure to catecholamines. Our results demonstrate that prolonged activation of alpha-adrenoceptors in blood vessels leads to down-regulation of PKC which may contribute to desensitization of contraction mediated by vasoconstrictors.


Effect of beta-adrenergic receptor antagonism on chloralose-induced hemodynamic changes in newborn lambs. alpha-Chloralose is an anesthetic commonly used in cardiovascular research. Using a chronically instrumented neonatal lamb model, we previously determined that chloralose has important effects on basal hemodynamics and arterial oxygen tension as compared with those of paired conscious control lambs. We wished to determine whether beta-adrenergic receptor stimulation accounted for chloralose-induced hemodynamic effects and to investigate the influence of chloralose and beta-adrenergic receptor antagonism on oxygen metabolism. In paired studies, five lambs were given chloralose intravenously (30 mg/kg i.v.) after propranolol (1 mg/kg i.v.) or saline control. The group pretreated with propranolol had reduced heart rate (HR 206 +/- 12 vs. 244 +/- 10 beats/min, p = 0.04) and cardiac output (CO 253 +/- 29 vs. 302 +/- 40 ml/min/kg, p = 0.005) 30 min after chloralose as compared with control; pretreatment with propranolol also attenuated the systemic hypertensive response to chloralose (77 +/- 8 vs. 89 +/- 5 mm Hg, p = 0.055). No difference in the response of stroke volume (SV), atrial or pulmonary arterial pressures, or pulmonary and systemic vascular resistances (PVR, SVR) were observed between treatment groups. No differences between propranolol and saline treatment groups were observed in arterial and mixed venous oxygen contents, arteriovenous (A-V) oxygen difference, oxygen extraction, or oxygen consumption; a reduction in oxygen delivery observed after propranolol as compared with saline was not altered by chloralose. We conclude that tachycardia and increase in CO induced by chloralose in lambs probably are mediated by beta-adrenergic receptor stimulation, which may be direct or indirect.(ABSTRACT TRUNCATED AT 250 WORDS)


Inhibition of platelet-activating factor fails to limit ischemia and reperfusion-induced myocardial damage. To determine the role of platelet-activating factor (1-O-hexa-decyl-2-acetyl-sn-glyceryl-phosphoryl-choline, PAF) in myocardial ischemic and reperfusion-induced injury, the effects of a PAF receptor antagonist (WEB 2086) were studied in an anesthetized canine model of ischemia (90 min) and reperfusion (6 h). Thirty minutes after onset of ischemia, WEB 2086 was administered as a bolus (20 mg/kg intravenously, i.v.) followed by a continuous 6-h infusion (10 mg/kg/h i.v.). Controls received vehicle alone (0.9% saline). Platelet aggregation was studied at baseline and at 1, 2, 4, and 6 h of drug administration and at the end of the reperfusion period. WEB 2086 treatment did not significantly affect platelet aggregation stimulated by ADP or arachidonic acid (AA). After 1 h of drug infusion, the ex vivo aggregatory response to exogenous (200 nM) PAF was ablated in WEB 2086-treated animals. WEB 2086 administration did not affect heart rate (HR) or mean arterial blood pressure (MAP) during the occlusion or reperfusion phases. During reperfusion of the ischemic tissue, left circumflex coronary artery (LCX) blood flow of WEB 2086-treated animals increased (p < 0.05) above control value. The area of the left ventricle at risk of infarct was not different between control and WEB 2086-treated groups. Infarct size was not significantly reduced in WEB 2086-treated animals. The results of our investigation using a 90-min ischemic period followed by 6-h reperfusion show that pharmacologic antagonism of PAF by WEB 2086 does not protect the heart against ischemia and reperfusion-induced injury.


Postischemic stunning: the two-phase model for the role of calcium as pathogen. The hypothesis proposed is that postischemic stunning occurs in two phases. The first and causative phase occurs very rapidly after the onset of reperfusion and is associated with cytosolic calcium overload with transiently normal mechanical function. If agents enhancing calcium influx are given at this early stage, they worsen subsequent stunning. Conversely, agents inhibiting calcium influx such as nisoldipine may lessen the extent of stunning. In the second phase (established stunning), there is hypocontractility and calcium antagonists given to isolated hearts can further impair mechanical function. Logically, agents enhancing calcium influx improve mechanical function. Unexpectedly, calcium antagonists given to large animal hearts in situ can improve established stunning, through mechanisms that are not well understood. The harmful effects of free radicals are not discounted but can be explained by early membrane damage with a consequent rise in cytosolic calcium during the early first phase of reperfusion.


The role of oxygen radicals during reperfusion. Oxy and hydroxy radicals produced during postischemic reperfusion may contribute to the mechanisms responsible for the sustained contractile dysfunction and ultrastructural injury that occur under these conditions. At the molecular level, the consequent peroxidation of membrane-located lipids (including membranes that delineate the sarcoplasmic reticulum, the mitochondria, and the myocytes) probably contributes to the associated loss of Ca2+ homeostasis. Protection against oxy and hydroxy radical-induced injury can be approached in several ways. Oxy and hydroxy radical formation can be limited, or the radicals "trapped." Alternatively, agents that protect membranes against lipid peroxidation-induced injury can be used. To determine whether the calcium antagonist nisoldipine has such a protective effect, isolated hearts were exposed to 0.9 mM H2O2 for short periods of time, and the functional recovery on removal of the H2O2 was used to assess the protective effect of 5 x 10(-9) M nisoldipine. In addition, further evidence of protection was obtained by exposing hearts to an oxy radical-generating system in the presence and absence of 10(-8) M nisoldipine and using the inhibitory effect of nisoldipine on the oxy radical-induced externalization of the endothelin-1 ETA binding sites to quantify protection.


Myocardial stunning following coronary angioplasty: protective effects of calcium-channel blockers. The beneficial effects of calcium-channel blockers against myocardial stunning have been tested in experimental studies, showing that, when added before or during ischemia, a protective effect against postischemia stunning is achieved. The present study was undertaken to test and compare the protective effect of calcium antagonists [nisoldipine (NIS) and nifedipine (NIF)] and nitrates (NIT) against myocardial stunning in patients with coronary artery disease undergoing percutaneous transluminal coronary angioplasty (PTCA) with prolonged inflation as PTCA represents a model of induced acute and severe ischemia for a brief period and might cause myocardial stunning. The study included 30 patients between the ages of 42 and 67 years, all with exercise-induced angina and single-vessel disease, with severe stenosis (80% to subtotal occlusion) localized on the left anterior descending artery and with the absence of collaterals on the coronary angiograms. Moreover, all patients had normal left ventricular (LV) overall function, as well as normal systolic thickening of the anterior wall, supplied by the diseased artery. Patients were randomized to a pre-PTCA treatment with NIT, 80-120 mg/day (10 patients), NIF, 40-60 mg/day (10 patients), and NIS, 10-20 mg/day (10 patients). Pre-PTCA treatment was initiated 7 days before the procedure and continued after. During the PTCA, at the first balloon inflation, an additional dose of 300 micrograms of NIT was injected into the left anterior descending artery through the balloon catheter in the patients in the NIT group, as well as 0.2 mg of NIF in NIF group patients and 0.05 mg of NIS in NIS group patients.(ABSTRACT TRUNCATED AT 250 WORDS)


Characterization of "hibernating" and "stunned" myocardium with focus on the use of calcium antagonists in "stunned" myocardium. In the initial seconds after a sudden reduction in coronary blood flow, a temporary mismatch between myocardial energy demand and supply exists. The mechanisms underlying the rapidly ensuing reduction in contractile function in the ischemic myocardium are still unknown. In the presence of some residual blood flow, a state of "perfusion-contraction matching" develops. The metabolic status of such hypoperfused myocardium improves, since myocardial lactate production is attenuated and creatine phosphate (CP), after an initial reduction, returns toward control values. The hypoperfused myocardium responds to inotropic stimulation by dobutamine. The recruitment of an inotropic reserve implies increased energy utilization. During inotropic stimulation, after partial normalization, lactate production is again increased, and CP is decreased again. Thus, a supply-demand imbalance that had been at least partially corrected by the ischemia-induced decrease in regional contractile function is precipitated again. A situation of chronic contractile failure in viable myocardium that normalizes upon reperfusion has been termed myocardial "hibernation." Myocardial "stunning" is characterized by a reversible postischemic contractile dysfunction despite full restoration of blood flow. The details of the underlying mechanisms are not clear. An inadequate energy supply and impaired sympathetic neurotransmission have been excluded. Potential mechanisms, which are not mutually exclusive, may include (a) damage of membranes by free radicals, (b) an increase in free cytosolic calcium during ischemia and reperfusion, and (c) a decrease in the calcium sensitivity of the myofibrils. The equally pronounced increases in regional contractility in normal and "stunned" myocardium during postextrasystolic potentiation and the infusion of calcium or the calcium-sensitizing agent AR-L-57, however, suggest an unchanged calcium sensitivity of reperfused myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)


Selectivity scale of calcium antagonists in the human cardiovascular system based on in vitro studies. The inhibitory effect of calcium antagonists has been studied on the calcium signal and on contractile activity in the human coronary and internal mammary arteries. We observed that rhythmic vasospasms, either spontaneous or evoked by serotonin and endothelin, were highly sensitive to calcium-channel inhibitors. Functional parameters describing the inhibition have been compared to binding parameters estimated in radioligand studies on membranes prepared from human coronary artery and from human heart. Taking the present studies and observations already published together, it was possible to build up a selectivity scale for diltiazem, verapamil, nifedipine, and nisoldipine. This showed that nisoldipine was more selective for coronary artery than the other calcium antagonists so far studied. Such a selectivity observed in functional studies on intact human preparations in vitro could be predicted considering the kinetic parameters of the interaction of nisoldipine with calcium channels.


Ventricular function and calcium handling during ischemia. Ischemia-induced ventricular dysfunction has been shown to be associated with increased diastolic and systolic intracellular concentrations of free, ionized calcium ([CA2+]i). The present study was designed to determine the effects of the calcium antagonist nisoldipine on the relationship between [Ca2+]i and left ventricular contraction and relaxation during ischemia and reperfusion on a beat-to-beat basis. Nine isovolumic coronary-perfused ferret hearts were made globally ischemic for 3 min and reperfused for 10 min. Ischemia and reperfusion were repeated during perfusion with buffer containing 10(-8) M nisoldipine. From the left ventricular developed pressure, the time to peak pressure and time to 50% pressure decline were obtained. [Ca2+]i was determined with the bioluminescent protein aequorin. Global ischemia caused a rapid decline in contractile function and a significant increase in diastolic [Ca2+]i from 0.35 to 0.81 microM and in systolic [Ca2+]i, from 0.61 to 0.96 microM. During reperfusion, [Ca2+]i returned to baseline while ventricular function was still impaired. Relaxation was more affected than systolic contractile function (Fig. 1). Nisoldipine significantly reduced the ischemia-induced rise in diastolic [Ca2+]i to 0.62 microM and in systolic [Ca2+]i to 0.77 microM and lessened the decrease in contractile function. Nisoldipine significantly accelerated the decline in [Ca2+]i during reperfusion and improved recovery of contractility and relaxation. These effects were associated with a significant diminution in ischemic lactate production. Taken together, our results provide direct quantitative evidence on a beat-to-beat basis that the calcium antagonist nisoldipine can ameliorate ischemia-induced abnormalities in [Ca2+]i handling, an effect that was associated with improved myocardial function during early reperfusion.


Specific coronary hemodynamic effects of nisoldipine and other vasoactive drugs. The specific coronary hemodynamic effects of different vasoactive drugs were studied using a randomized, double-blind protocol in the "normal" contralateral artery after performing single-vessel coronary angioplasty. The intracoronary administration of 50 micrograms of nisoldipine resulted in an increase in epicardial diameter (+19%; p = 0.0001) and in coronary blood flow (+47%; p = 0.003), but the flow reserve decreased (-20%; p = 0.001). In placebo-treated patients, all parameters proved to be very stable and no significant changes were found. In a second study, 500 micrograms of diltiazem i.c. was administered to 20 patients, who were first randomized to pretreatment with either placebo (n = 10) or isosorbide dinitrate (0.5 micrograms/kg/min infusion; n = 10). There were increases in epicardial diameter (+10%; p = 0.0001) and coronary flow (+30%; p = 0.0001) in all patients. These changes were comparable in patients pretreated with placebo or nitrates but the reduction in coronary flow reserve was only significant in patients pretreated with placebo (+19%; p = 0.0008). In a third study, the hemodynamic effects of the intracoronary application of SIN-1 (500 micrograms), the active metabolite of molsidomine, were studied. There was a consistent increase in epicardial diameter (+26%; p < 0.0001) but the response at the microvascular level was heterogeneous and characterized by a trend to increased blood flow (+25%; p = 0.11) and decreased coronary vascular resistance (-18%; p = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)


Stunned and hibernating myocardium: possibility of intervention. There are several potential outcomes of myocardial ischemia. When ischemia is severe and prolonged, irreversible damage occurs and there is no recovery of contractile function. When myocardial ischemia is less severe but still prolonged, myocytes may remain viable but exhibit depressed contractile function. Under these conditions, reperfusion restores complete contractile performance. This type of ischemia, leading to a reversible, chronic left ventricular dysfunction, has been termed hibernating myocardium. The difference between this condition and that described before, i.e., prolonged ischemia, which results in further damage on reperfusion, is, most likely, related to residual coronary flow. In the hibernating myocardium, which is always supplied by a narrow coronary artery, blood flow is not low enough to cause progression toward tissue necrosis, but it is low enough to cause pH changes that, in turn, are responsible for the downregulation of myocardial contractility. The level of underperfusion is sufficient to maintain aerobic metabolism of the quiescient myocardium as demonstrated by the absence of lactate and creatine phosphokinase release. There are no doubts that revascularization is essential for hibernated myocardium, and the clinical goal to achieve is the possibility of accurately distinguishing viable from infarcted tissue. A third possible outcome of myocardial ischemia is a postischemic ventricular dysfunction or myocardial stunning. This term describes a transient mechanical dysfunction that persists on reperfusion after a short period of ischemia, despite the absence of irreversible damage. There are numerous clinical conditions in which stunning might manifest.(ABSTRACT TRUNCATED AT 250 WORDS)


Effects of calcium antagonists in patients with coronary disease and heart failure: left ventricular function following nisoldipine measured by radionuclide ventriculography. Thirty-two patients with chronic heart failure were investigated with radionuclide ventriculography at rest and during exercise. The global ejection fraction (EF), ejection rate, ejection time, and filling rate were measured. The patients were subdivided into three subgroups: patients with extremely (< 25%), moderately (25-33%), and mildly decreased EF (33-40%). All patients were investigated by thallium-201 myocardial scintigraphy and the correlation between ejection parameters and infarct size was investigated. In a random protocol 17 patients (14 men, 3 women, mean age of 54.6 years) received beta-acetyldigoxin at a dose of 0.3 mg daily over 4 weeks, 15 patients (13 men, 2 women, mean age of 58.2 years) received nisoldipine at a dose of 20 mg daily. Patients on digitalis showed a further lowering of the extremely decreased EF (-1%), but in patients with moderately decreased EF, digoxin produced a marked increase in EF of +8% (p < 0.001). In mildly decreased EF, there was no significant change (+0.3%, n.s.). Nisoldipine produced an increase in pump function (+2%) in the group with extremely decreased EF up to 9% in some individual cases. A significant increase (+5%) was achieved in moderately decreased EF, while patients with mildly decreased EF did not respond. Thus, nisoldipine may be indicated in the treatment of heart failure after repeated myocardial infarctions, in particular in patients with severely decreased ejection fraction.


Effect of calcium antagonists on exercise tests. The aim of this study was to investigate the anti-ischemic and antianginal activity and the duration of the new dihydropyridine calcium blocker nisoldipine (NIS) in patients with stable angina pectoris. The research was carried out on 16 patients, all male, 41-68 (mean of 58) years of age, with stable angina pectoris and fixed ischemic threshold (variations < 15%). After a 10-day washout period, patients were randomized to treatment with either 10 mg of nisoldipine or placebo (PL), twice daily for 21 days, according to a double-blind, crossover design. Patients underwent maximal symptom-limited exercise testing at 10 W/min on a bicycle ergometer, twice during the washout period, and once at the end of each treatment period, 3 and 12 h after oral administration of the drugs. In comparison with placebo, nisoldipine increased the ischemic threshold (N, 704 +/- 45 s; PL, 548 +/- 35 s; p < 0.01) and anginal threshold (N, 766 +/- 44 s; PL, 699 +/- 42 s; p < 0.01) for at least 12 h, and the ST-segment depression significantly decreased at maximal work (PL, 2.4 +/- 0.1 mm; N, 1.8 +/- 0.2 mm; p < 0.01) and at maximal common work (PL, 2.4 +/- 0.1 mm; N, 1.15 +/- 0.2 mm; p < 0.01). Similar to placebo the rate-pressure product was not significantly changed at higher submaximal effort after N, but it was significantly increased at the level of ischemic threshold, suggesting an increase in coronary blood flow to ischemic zones. Nisoldipine possesses anti-ischemic and antianginal activity lasting at least 12 h. This activity seems to be due to an increase in coronary blood flow to ischemic zones.


Effects of nisoldipine in coronary artery disease: a radioisotopic approach. The clinical, electrocardiographic, and scintigraphic effects of oral administration of nisoldipine were investigated using two separate study protocols. In the first, the acute effects of nisoldipine were evaluated by means of nuclear ventricolography and demonstrated no deleterious effects on global contractility and an amelioration of several hypokinetic segments. In the second protocol, myocardial perfusion effects were evaluated by means of tomoscintigraphy. An improvement of segmental uptake of thallium was caused by nisoldipine. The addition of atenolol markedly reduced the rate-pressure product and further improved myocardial perfusion.


Reversible and irreversible left ventricular dysfunction after acute myocardial infarction. Left ventricular function after acute myocardial infarction depends on several mechanisms leading to left ventricular remodeling: (a) infarct size and healing and (b) adaptive changes involving both the dysfunctioning but viable myocardium (hibernating and stunned myocardium) and the nonischemic myocardium. The prognosis after acute myocardial infarction is strongly related to regional and global left ventricular function and the loss of dysfunctioning viable myocardium is a main factor in the worsening in left ventricular function in survivors of the acute phase. Thus, medical strategies should exert their beneficial effect on the "mechanical instability" of ventricular myocardium by saving the viable myocardium. beta-Blocker therapy has been shown to be effective in improving the prognosis via anti-ischemic and antiarrhythmic actions. The combination of metoprolol and nisoldipine seems to be able to preserve the contractile function of viable myocardium in the first 6 months after acute myocardial infarction.


Effects of prolonged nisoldipine administration on the "hibernating" myocardium. To assess the effects of nisoldipine on chronically underperfused myocardial areas ("hibernating myocardium"), the global and regional left ventricular (LV) function was analyzed before and after 2 months of double-blind monotherapy with nisoldipine (10 mg twice daily) or placebo in 17 patients with a previous anterior myocardial infarction. The baseline LV ejection fraction ranged from 34 to 51%, and no patient had heart failure. Compared to placebo, nisoldipine significantly lowered the LV systolic pressure and end-diastolic pressure (-3 vs. +6 mmHg with placebo; p < 0.01) and the LV pressure at the time of mitral valve opening (-2.0 +/- 3.4 vs. +3.5 +/- 3.0 mm Hg; p < 0.01). Despite this reduction in driving pressure, the global LV early peak filling rate improved only with nisoldipine and this improvement was related to a selective increase in the expansion rate of the anterior areas, from 1,010 +/- 360 to 1,339 +/- 496 mm2/s (p < 0.001). The time to regional peak filling rate (-8%; p < 0.01), the asynchrony of diastolic wall motion, and the regional ejection fraction (33 +/- 10 to 38 +/- 12%; p < 0.001) also improved in the anterior areas with nisoldipine but not with placebo. In contrast, in the inferior control zones, the regional ejection fraction and filling rate remained unchanged, both when compared to baseline and to placebo. In conclusion, prolonged nisoldipine therapy had no significant effect on the normal myocardium but improved systolic and diastolic function in hypokinetic areas.(ABSTRACT TRUNCATED AT 250 WORDS)


Kininogenase of the aortic wall in spontaneously hypertensive rats. We determined kinin-generating activity (kininogenase) in the thoracic aorta of spontaneously hypertensive rats (SHRs) at age 5 and 15 weeks and in appropriately age-matched Wistar-Kyoto (WKY) rats. Aorta homogenates were incubated with partially purified dog kininogen, and the resulting kinins were extracted with ethanol. The kinins were determined by a sensitive kinin radioimmunoassay (RIA). Kininogenase activity was expressed as mean +/- SEM, picogram kinin generated/mg x protein/h. Active kininogenase in SHR was approximately one-third in 5-week-old and about one-fifth in 15-week-old rats when compared with their normotensive controls. Total kininogenase activity in SHRs was approximately 80% and 58% of the normotensive controls at ages 5 weeks and 15 weeks, respectively. Active enzyme was 14% of the total in 5-week-old SHRs, and it was only 5% of the total in 15-week-old SHRs. It seems unlikely that the changes in kininogenase are secondary to hypertension because blood pressor is only marginally elevated at 5 weeks according to the literature. We hypothesize that genetic hypertensive rats may suffer from an inherent deficiency in the kininogenase activity of the vascular wall. The deficiency may also be in the mechanism of activation of precursor enzyme.


The angiotensin I-converting enzyme (kininase II): molecular organization and regulation of its expression in humans. Protein sequencing and molecular cloning of human endothelial angiotensin I-converting enzyme (ACE; kininase II), have led to a description of the structure of the enzyme and to several questions concerning the intracellular maturation of ACE and the mechanisms of enzyme action. With the help of recombinant ACE expression in mammalian cells and site-directed mutagenesis, a model for the maturation of ACE in endothelial cells has been proposed. This model comprises transmembrane anchoring of the membrane-bound ACE near its carboxyterminal extremity, and post-translational cleavage of the anchor in the secreted form. The endothelial ACE displays a high degree of internal homology between two large peptidic domains that each bears a consensus sequence for zinc binding and therefore a putative active site. The testicular ACE, however, encoded from the same gene by a shorter mRNA, contains only the carboxyterminal half of endothelial ACE and therefore a single active site. Expression of ACE mutants with only one intact homologous domain, however, indicates that in endothelial ACE both domains are enzymatically active. Further characterization of these two active sites of endothelial ACE is in progress. In humans, population studies have indicated that the large interindividual variability in plasma ACE levels is partly genetically determined and under the influence of a major gene effect. This was later confirmed and extended by the observation of an insertion-deletion polymorphism of the ACE gene that is associated with the level of ACE in plasma. The clinical implications of these observations are discussed.


Bradykinin degrading activity in cultured human endothelial cells. The role of angiotensin-converting enzyme (ACE), neutral endopeptidase 24.11 (NEP), and other peptidases in the endothelial degradation of bradykinin was investigated in cultured human umbilical vein endothelial cells (HUVEC). The major part of the kininase II activity on intact cells was attributed to ACE activity, the minor part to NEP activity. Amastatin, as aminopeptidase inhibitor, and DL-2-mercaptomethyl-3-guanidinoethyl-thiopropionic acid (MGTA), an inhibitor of kininase I, did not affect endothelial kininase activity. The decline of the bradykinin concentrations in the supernatant of intact endothelial monolayer indicated a total kininase activity of 289 +/- 27 fmol/min/dish. The calculated activity of ACE was 223 fmol/min/dish and the neutral endopeptidase activity was 51 fmol/min/dish. Thus, ACE and neutral endopeptidase are the main kininases in the degradation of bradykinin by intact endothelial cells. In contrast to the intact endothelial monolayers, in homogenates additional kininase activity was found which was not affected by either ACE and NEP inhibitors nor by amastatin and MGTA.


Effect of bradykinin on arteries and veins in systemic and pulmonary circulation. Bradykinin is a potent vasodilating and natriuretic peptide, which is potentiated by angiotensin-converting enzyme (ACE) inhibitors. In our investigations we studied the effect of bradykinin on systemic and pulmonary circulation as well as on dorsal hand vein tone. The effects of bradykinin on systemic and pulmonary circulation were tested by injection of bradykinin into the right atrium. Parameters were determined for blood pressure, cardiac output, ECG and mean pressure in pulmonary artery. Heart rate, total peripheral resistance, pulmonary vascular resistance, and pulmonary arteriolar resistance were calculated by these measured parameters. The data raised in our investigations showed clearly that bradykinin reduced blood pressure by reducing total peripheral vascular resistance in a dose-dependent manner. In pulmonary circulation bradykinin develops a direct effect. All circulatory actions of bradykinin are not mediated by prostaglandins, since inhibition of prostaglandin synthesis by indomethacin (100-150 mg) was without any effect. ACE inhibition by ramipril (5 mg) or captopril (50 mg) potentiated all effects of bradykinin about 20- to 50-fold, whereas it decreased angiotensin I effects only about four- to fivefold. These results suggest, that endogenous kinins, if they will be similarly potentiated by ACE inhibition like the exogenous bradykinin in our experiments, might play an important role in the blood pressure lowering effect of ACE inhibitors. Dorsal hand vein tone was reduced by bradykinin too, indicating that kinins can lower cardiac preload by increasing venous blood pooling.


Antagonizing and measurement: approaches to understanding of hemodynamic effects of kinins. Hemodynamic effects of the kallikrein-kinin system can be investigated by experimental administration of specific kinin antagonists and by measurement of kinin levels in the circulating blood. In conscious normal rats, the bradykinin analog B4162 blunts the hypotensive effect of exogenous bradykinin. This kinin antagonist has no blood pressure effect in control rats, but it enhances the pressor effect of vasoconstrictor substances such as vasopressin or angiotensin II when they are infused at subpressor doses. Endogenous kinins may therefore participate in blood pressure regulation by antagonizing pressor substances. Plasma levels of endogenous kinins are normally in the low picomolar range. They are rapidly generated and destroyed in biological fluids. Thus, measurement of plasma kinins requires sensitive assays based on high-affinity antibodies and careful sample-handling techniques. Nonpolar solid-phase extraction on phenylsilylsilica provides a rapid, reliable, and easy extraction of kinins from plasma with constant and high recoveries.


Changes in peripheral sympathetic outflow of pithed spontaneously hypertensive rats after bradykinin and DesArg-bradykinin infusions: influence of converting-enzyme inhibition. Because converting enzyme and kininase II are identical enzymes and probably influence both the biosynthesis of angiotensin II and the metabolism of bradykinin, we investigated the effects of bradykinin and desArg-bradykinin on the sympathetic outflow of pithed spontaneously hypertensive rats (SHRs) before and after acute or chronic inhibition of the converting enzyme by ramipril. Sympathetic outflow was induced by preganglionic electrical stimulation of the spinal cord and measured as circulating, stimulation dependent norepinephrine and epinephrine by high-performance liquid chromatography (HPLC) and electrochemical detection. Bradykinin increased dose-dependently norepinephrine and epinephrine release, particularly when converting enzyme was inhibited. DesArg-bradykinin did not influence norepinephrine outflow but caused a dose-dependent increase in epinephrine release only after converting-enzyme inhibition. It is suggested that both bradykinin and desArg-bradykinin could compensate for the lack of effect of angiotensin II on sympathetic outflow.


Influence of angiotensin-converting enzyme inhibition on sympathetic neurotransmission: possible roles of bradykinin and prostaglandins. Effects of angiotensin-converting enzyme (ACE) inhibitors on sympathetic neurotransmission have generally been ascribed to their ability to block angiotensin II (Ang II) formation, but they also inhibit the degradation of vasoactive kinins, such as bradykinin. The latter may, in turn, lead to enhanced prostaglandin formation. Prostaglandins have been reported to influence sympathetic neurotransmission at different sites; much less is known about the influence of bradykinin due to the lack (until recently) of specific and effective bradykinin receptor antagonists, and difficulties with measurements of true plasma or tissue levels of bradykinin. Bradykinin may modulate sympathetic activity via a central stimulatory action and via activation of sensory input to the central nervous system; however, the importance of bradykinin for central effects of ACE inhibition remain to be established. At the sympathetic neuro-effector junction, results are more conflicting. Thus, bradykinin has been reported to enhance or reduce peripheral noradrenergic transmission or even lack any effect. Possible explanations for the differing results obtained include species and/or tissue differences in the responses to bradykinin. Also, the effects of bradykinin may be influenced by enhanced formation of prostaglandins and/or endothelium-derived relaxing factor (EDRF), which may contribute to the confusion. As most studies have been performed under in vitro conditions and with high doses of bradykinin, the physiological relevance of the data may be questioned.(ABSTRACT TRUNCATED AT 250 WORDS)


Bradykinin-degrading enzymes: structure, function, distribution, and potential roles in cardiovascular pharmacology. Bradykinin is susceptible to degradation by a variety of endo- and exopeptidases. These include aminopeptidase P, meprin, endopeptidase 24.15, prolyl endopeptidase, neutral endopeptidase 24.11, angiotensin I-converting enzyme, carboxypeptidase N, carboxypeptidase M, and deamidase. These peptidases are widely distributed in various tissues and cells in the body, and their subcellular locations vary as well. Because bradykinin is inactivated (for binding the B2 receptor) when any of its peptide bonds are cleaved, all of these enzymes qualify as potential "kininases" in vivo; however, the importance of a particular enzyme as a kininase will depend on its localization, access to bradykinin, and the presence of other peptidases. In addition, these peptidases can cleave a variety of other peptide hormone substrates. Determination of the importance of a peptidase in the inactivation of bradykinin during a particular physiological response can be difficult, but specific peptidase inhibitors and kinin receptor antagonists are useful tools in investigating these questions.


Anti-idiotypic antibodies against the kinin receptor. Three sets of monoclonal antibodies against bradykinin (MBK1, MBK2, and MBK3) were generated by somatic cell fusion, characterized by their peptide specificity, and compared with the known ligand specificity of the kinin receptor subtypes. By these criteria, the paratope of MBK3 resembled the B2 receptor binding site, whereas MBK1 shared principal binding characteristics with the B1 receptor. Anti-idiotypic antibodies against MBK1, MBK2, and MBK3 were raised in rabbit and sheep. Specificity of the network components was verified by inhibition experiments on the level of peptide, idiotype, and anti-idiotype. Anti-idiotypic antibodies against MBK3 recognized a conformation-dependent epitope which was binding site-related. Binding studies on human foreskin fibroblasts and guinea pig ileum showed mutual displacement of the anti-idiotypic antibody and bradykinin at the binding site pointing to a specific interaction of the antibody with the receptor from various species. An agonist activity of the antibodies, demonstrated in human (inositolphosphate pathway) and mouse (prostaglandin pathway) fibroblasts indicated that the anti-idiotypes bear an internal image of the ligand epitope. This molecular mimicry, which was further substantiated by the detection of bradykinin-specific anti-anti-idiotypic antibodies, provides the structural basis for the observed cross-reactivity over species borders.


Role of endothelium-derived bradykinin in the control of vascular tone. We have investigated the effects of angiotensin-converting enzyme (ACE) inhibitors on intracellular Ca2+ levels in human cultured endothelial cells and on endothelial autacoid formation in endothelium-intact bovine coronary arteries and in isolated perfused rabbit and rat hearts. Incubation of cultured endothelial cells with ramiprilat (0.3 microM) caused a maintained increase in resting intracellular Ca2+. This effect was long-lasting, accompanied by an increased formation of both nitric oxide (NO) and prostacyclin (PGI2), and was abolished by the specific B2-kinin receptor antagonist Hoe 140. Ramiprilat also significantly enhanced the increase in intracellular Ca2+ elicited by bradykinin (3 nM). In endothelium-intact bovine coronary arteries, moexiprilat (0.3 microM), like bradykinin (30 nM), caused a nearly twofold increase in the vascular cGMP content which was abolished by both NG-nitro-L-arginine (30 microM) and removal of the endothelium. The functional consequences of this ACE inhibitor-induced increase in vascular cGMP content were reflected by a distinct relaxation of the coronary segments preconstricted with prostaglandin F2 alpha. In the isolated perfused rabbit heart, ramiprilat (0.3 microM) affected neither resting vascular tone nor endothelial autacoid release; however, the vasodilation and release of PGI2 in response to exogenously applied bradykinin (10 nM) were significantly enhanced by ramiprilat. This effect was also seen using moexiprilat (0.1 microM) in the isolated perfused rat heart. Although these findings suggest that endothelium-derived bradykinin is not involved in the control of resting vascular tone in the coronary microcirculation of the rabbit and the rat, there appears to be significant ACE activity to modulate bradykinin-induced endothelial autacoid formation.(ABSTRACT TRUNCATED AT 250 WORDS)