disclosed herein is a method of treating chf by administering a therapeutically effective dose of at least one nitroxyl ( hno / no − ) donating compound to a subject experiencing heart failure . in particular embodiments the hno / no − donating compound is ipa / no . in other particular embodiments the hno / no − donating compound is piloty &# 39 ; s acid . also disclosed herein is a method of treating chf by administering a therapeutically effective dose of at least one hno / no − donating compound in combination with a therapeutically effective dose of at least one positive inotropic agent to a subject experiencing heart failure . in particular embodiments the hno / no − donating compound is a diazeniumdolate , such as ipa / no , and the positive inotrope is a beta - adrenergic agonist , such as dobutamine . additionally , in particular embodiments of the methods described above , the hno / no − donating compound or the combination of the hno / no − donating compound and the positive inotropic compound are used to treat class iii chf , or other non - acute chf . in still other embodiments the methods are used to treat acute chf . also disclosed is a method of treating chf in a subject receiving beta - antagonist therapy by administering a therapeutically effective dose of at least one hno / no − donating compound . in particular embodiments the hno / no − donating compound is a diazeniumdolate , such as angeli &# 39 ; s salt . a nitroxyl donor is an agent or compound that provides a physiologically effective amount of hno or no − ( hno / no − ). the hno / no − donating compound is any compound that donates hno / no − and has a safety profile indicating the compound would be tolerated by a subject in the amount necessary to achieve a therapeutic effect . one of ordinary skill in the art would be able to determine the safety of administering particular compounds and dosages to live subjects . such a compound includes any compound having the formula wherein j is an organic or inorganic moiety , m + x is a pharmaceutically acceptable cation , wherein x is the valence of the cation , a is 1 or 2 , b and c are the smallest integers that result in a neutral compound , and wherein the compound is administered under conditions that cause it to release hno / no − . the compounds of formula i are known generally as diazeniumdolates because they contain the n - oxy - n - nitroso complex . angeli &# 39 ; s salt is a compound of formula i that disassociates under physiological conditions to donate hno / no − . other diazeniumdolates that disassociate under physiological conditions to generate hno / no − , such as ipa / no or sulfi / no ( n - nitrosohydroxylamine - n - sulfonate / ammonium salt ), are also used in performing the method . additionally , analogs and derivatives of such compounds can be used . moreover , conditions , such as the oxidation state of the environment , can be altered to cause such compounds to donate hno / no − . an analog is a molecule that differs in chemical structure from a parent compound , for example a homolog ( differing by an increment in the chemical structure , such as a difference in the length of an alykl chain ), a molecular fragment , a structure that differs by one or more functional groups , or a change in ionization . structural analogs are often found using quantitative structure activity relationships ( qsar ), with technologies such as those disclosed in remington : the science and practice of pharmacology , 19 th edition ( 1995 ), chapter 28 . a derivative is a biologically active molecule derived from the base structure . wang et al ., “ new chemical and biological aspects of s - nitrosothiols ,” curr . chem ., 7 ( 8 ): 821 - 34 ( 2000 ), describes no − formation from heterolytic decomposition of s - nitrosothiol compounds . thus , s - nitrosothiol compounds such as s - nitroso - l - cystine ethyl ester , s - nitroso - l - cystine , s - nitroso - glutathione , s - nitroso - n - acetyl - cystine , s - nitroso - 3 - mercaptoetanol , s - nitroso - 3 - mercaptopropanoic acid , s - nitroso - 2 - aimonethanethiol , s - nitroso - n - acetyl penicillamine ( snap ), s - nitrosocaptopril , as well as others are also used in performing the provided method . in particular , s - nitrosoglutathione ( gnso ) has been reported as capable of being reduced to hno / no − in the presence of thiols . hogg et al ., biochem . j ., 323 : 477 - 481 ( 1997 ). piloty &# 39 ; s acid ( benzenesulfohydroxamic acid ) is a hydroxamic acid ( x (═ o ) nhoh ) that donates hno / no − and is useful in performing the provided methods . other hydroxamic acids that donate hno / no − , in particular , other sulfohyrdroxamic acids and their derivatives are also useful . thionitrates ( r —( s )— no 2 , wherein r is a polypeptide , an amino acid , a sugar , a modified or unmodified oligonucleotide , a straight or branched , saturated or unsaturated , aliphatic or aromatic , substituted or unsubstituted hydrocarbon , or a heterocylclic group ) that donate hno / no − are useful in performing the methods provided . in particular , such compounds that form disulfide species are useful . one of ordinary skill in the art would be able to determine these and other compounds capable of donating hno / no − . also included in this term is direct administration of hno / no − . compositions comprising more than one hno / no − donating compound are also used . for example , ipa / no and another compound that dissociates to generate hno / no − for example , piloty &# 39 ; s acid , are used to treat heart failure . in particular embodiments the hno / no − donating compound is administered in the form of a pharmaceutical composition . a pharmaceutical composition comprising an effective amount of the hno / no − donating compound as an active ingredient could be easily prepared by standard procedures well known in the art , with pharmaceutically acceptable non - toxic solvents and / or sterile carriers , if necessary . such preparations are administered orally or in injectable form , or directly to myocardial tissue . in other embodiments the hno / no − donor is administered without a pharmaceutical carrier . in particular embodiments the hno / no − donor is administered by a short - term infusion , such as for 5 to 20 minutes . in other embodiments the hno / no − donor is administered by a long - term infusion , such as from 3 - 4 hours . the hno / no − donated by angeli &# 39 ; s salt retains its beneficial effects during 3 - 4 hours of perfusion . the dose of the hno / no − donating compound is a therapeutically effective dose . a therapeutically effective dose of an hno / no − donating compound comprises a dose effective to increase contractility in a subject experiencing heart failure . optimizing therapy to be effective across a broad population can be performed with a careful understanding of various factors to determine the appropriate therapeutic dose , in view of the inventors &# 39 ; disclosure that these agents cause a positive inotropic effect as well as venous dilation . in particular embodiments , an infusion of 10 micrograms ( μg )/ kilogram of body weight ( kg )/ minute ( min ) is administered for 5 - 20 min to treat acute heart failure . in one example , the agent administered at this dose is angeli &# 39 ; s salt . in other embodiments an infusion of 2 . 5 μg / kg / min is administered for 5 - 20 min to treat acute heart failure . in one example , the agent administered at this dose is ipa / no . a positive inotrope is an agent or compound that causes an increase in myocardial contractile function . such an agent includes a beta - adrenergic receptor agonist , an inhibitor of phophodiesterase activity , and calcium - sensitizers . beta - adrenergic receptor agonists include , among others , dopamine , dobutamine , terbutaline , and isoproterenol . analogs and derivatives of such compounds are also used . for example , u . s . pat . no . 4 , 663 , 351 describes a dobutamine prodrug that can be administered orally . one of ordinary skill in the art would be able to determine these and other compounds that are capable of causing positive inotropic effects and also additional beta - agonist compounds . in particular embodiments the beta - receptor agonist is selective for the beta - 1 receptor . however , in other embodiments the beta - agonist is selective for the beta - 2 receptor , or is not selective for any particular receptor . additionally , compositions comprising more than one positive inotropic agent are used . for example , dobutamine and isoproterenol are used to treat heart failure . in particular embodiments the positive inotropic agent is administered in combination with the hno / no − donor . the combined administration of the hno / no − donor and the positive inotropic agent comprises administering the hno / no − donor either sequentially with the positive inotropic agent for example , the treatment with one agent first and then the second agent , or administering both agents at substantially the same time , wherein there is an overlap in performing the administration . with sequential administration a subject is exposed to the agents at different times , so long as some amount of the first agent , which is sufficient to be therapeutically effective in combination with the second agent , remains in the subject when the other agent is administered . treatment with both agents at the same time can be in the same dose , such as a physically mixed dose , or in separate doses administered at the same time . in particular embodiments the positive inotropic agent is administered in the form of a pharmaceutical composition . a pharmaceutical composition comprising an effective amount of the positive inotropic agent as an active ingredient could be easily prepared by standard procedures well known in the art , with pharmaceutically acceptable non - toxic solvents and / or sterile carriers , if necessary . such preparations are administered orally or in injectable form , or directly to myocardial tissue . in other embodiments the positive inotropic agent is administered without a pharmaceutical carrier . the dose of the positive inotropic agent is a therapeutically effective dose . in particular embodiments positive inotropic agent is administered at a dose of between 2 and 20 μg / kg / min . in certain examples dobutamine is administered at this dose . however , in other embodiments , higher and lower dosages are administered to subjects experiencing heart failure . for example , a dose of 0 . 5 μg / kg / min is administered , or a dose of 40 μg / kg / min is administered . optimizing therapy to be effective across a broad population can be performed with a careful understanding of various factors to determine the appropriate therapeutic dose , in view of the inventors &# 39 ; disclosure that the positive inotropic agent is administered in combination with an hno / no − donor . in particular embodiments an hno / no − donor is administered to a subject experiencing heart failure that is receiving beta - antagonist therapy . a beta - antagonist ( also known as a beta - blocker ) includes any compound that effectively acts as an antagonist at a subject &# 39 ; s beta - adrenergic receptors , and provides desired therapeutic or pharmaceutical results , such as diminished vascular tone and / or heart rate . in particular embodiments the beta - antagonist is selective for a particular receptor , such as the beta - 1 receptor . in other embodiments the beta - antagonist is not selective for any particular beta receptor . beta - antagonizing agents include metoprolol , bisoprolol , bucindolol , carvedilol , timolol , propranolol , pindolol , and atenolol . one of ordinary skill in the art would be able to identify these and other compounds that are capable of acting as beta - adrenergic antagonists at a subject &# 39 ; s beta - adrenergic receptors . a subject who is receiving beta - antagonist therapy is any subject to whom a beta - antagonist has been administered , and in whom the beta - antagonist continues to act as an antagonist at the subject &# 39 ; s beta - adrenergic receptors . in particular embodiments a determination of whether a subject is receiving beta - blocking therapy is made by examination of the subject &# 39 ; s medical history . in other embodiments the subject is screened for the presence of beta - blocking agents by chemical tests , such as high - speed liquid chromatography as described in thevis et al ., biomed . chromatogr ., 15 : 393 - 402 ( 2001 ). the administration of an hno / no − donating compound either alone , in combination with a positive inotropic agent , or to a subject receiving beta - antagonist therapy , is used to treat heart failure of all classifications . in particular embodiments an hno / no − donating compound is used to treat early - stage chronic heart failure , such as class ii heart failure . in other embodiments an hno / no − donating compound is used in combination with a positive inotropic agent , such as isoproterenol to treat class iv heart failure . in still other embodiments an hno / no − donating compound is used in combination with a positive inotropic agent , such as isoproterenol to treat acute heart failure . in some embodiments , when hno / no − is used to treat early stage heart failure , the dose administered is lower than that used to treat acute heart failure . in other embodiments the dose is the same as is used to treat acute heart failure . the following are non - limiting examples of particular embodiments of the methods provided herein . this example demonstrates that infusion of an hno / no − donor caused positive inotropic effects in failing myocardium . further , infusion of an hno / no − donor complemented the positive inotropic effect of dobutamine , as opposed to the impairment of dobutamine &# 39 ; s positive inotropic effect observed with no • donors . additionally , when compared with an infusion of angeli &# 39 ; s salt designed to cause a systemic blood pressure decrease nearly equivalent to that caused by ipa / no , the hno / no − donor ipa / no exerted a stronger positive inotropic effect . the effect of hno / no − donated by as ( 10 micrograms ( μg )/ kilogram ( kg )/ minute ( min ) for 5 - 20 min ) and ipa / no ( 2 . 5 - 5 . 0 μg / kg / min for 5 - 20 min ) on basal cardiovascular function was tested in mongrel dogs . studies were performed at a constant heart rate during atrial pacing ( 130 - 160 beats per minute ). myocardial effects produced by hno / no − donating compounds were compared to those produced by the no • donors dea / no and nitroglycerin at doses titrated to achieve the same decline in systolic pressure ( a measure of systemic blood pressure ) as the hno / no − donors . hemodynamic data was sampled at 250 hertz ( hz ) and steady - state and pressure - dimension parameters were derived . since in vivo cardiac contractility assessment requires separation of the effects of chamber loading , pressure - volume relation indexes , specifically , the end - systolic elastance ( ees ), and the slope of dp / dt max - end - diastolic dimension ( d edv ) relations were employed . isovolumic relaxation was derived from pressure decay waveforms assuming a nonzero decay asymptote . serum concentrations of nitrite and nitrate were determined by a modified griess assay , with and without prior chemical reduction of nitrate to nitrite using vcl 3 . serum stored at − 70 ° c . was deproteinized by ultrafiltration ( 30 kilodalton ( kd ) cut - off , centricon , sartorius ) at 4 ° c ., and absorbance at 540 nanometer ( nm ) read using a plate reader ( perkin elmer hts 7000 bioassay reader controlled by tecan winselect software ) after a 37 ° c . incubation with griess reagents for 30 - 45 min . with reference to fig1 , each compound tested was administered in doses titrated to achieve nearly equivalent end systolic pressures ( pes ) in order to allow comparison between equivalent levels of dilation . angeli &# 39 ; s salt and ipa / no caused significant increases in contractility during heart failure as measured by ees , d edv , and prsw . these increases were much greater than the small increases observed with dea / no and were opposite of the negative inotropic effects observed with nitroglycerin . additionally , both angeli &# 39 ; s salt and ipa / no reduced the cardiac load as measured by edv ( preload ) and ea ( afterload ). surprisingly , ipa / no caused a greater increase in cardiac contractility than angeli &# 39 ; s salt as measured by ees , which , being load - independent , is a good parameter for assessing myocardial contractility . this is especially surprising because the doses of ipa / no were one - half to one - quarter the doses of angeli &# 39 ; s salt . with reference to fig2 , the administration of hno / no − exhibited a positive inotropic effect , which was not dependent on cardiac load . as illustrated by the measurements of ees and prsw for both loaded and unloaded states , hno / no − exerted a nearly equivalent positive inotropic effect regardless of cardiac load . this indicates that the contractility increases caused by hno / no − are primary as opposed to secondary effects . in contrast , with reference to fig3 , the minor positive inotropic effects observed with the administration of no • ( dea / no ) were reversed when the heart was under cardiac load conditions , that is at matched end - diastolic volume . moreover , fig4 illustrates that administration of the no • donor nitroglycerin caused contractility to decrease when administered alone , and caused an even greater negative inotropic effect under loading conditions . this indicates that the minor contractility increase observed with dea / no is merely secondary to the vasodilatory effects of the compound . that is , no • has no direct positive inotropic effects because any increases in contractility were abolished upon volume repletion . with reference to fig5 , administration of as and ipa / no resulted in a greater positive inotropic effect than administration of dobutamine alone . for example , administration of as resulted in a more than doubling of ees over administration of dobutamine alone . in contrast , administration of dea / no and nitroglycerin reduced the positive inotropic effect of dobutamine , as illustrated by the decrease in ees when the dobutamine was administered with dea / no and ntg . this example demonstrates that the positive inotropic effect of hno / no − is a function of its stimulation of calcitonin gene - related peptide ( cgrp ) signaling rather than a function of beta - agonism . to test the relation between the inotropic action of hno / no − and calcitonin gene - related peptide ( cgrp ) signaling , cgrp receptors in mongrel dogs were antagonized using the selective antagonist cgrp 8 - 37 ( 400 μg in 30 milliliters ( ml ) of saline bolus , then 2 . 6 μg / kg / min for 15 min ). plasma cgrp levels measurements were performed by sampling the blood of the dogs . blood samples ( 2 . 5 ml ) were withdrawn from arterial , venous , and coronary sinus catheters . after sampling , catheters were flushed with heparanized saline . samples were centrifuged at 1600 times gravity ( g ) for 20 minutes at 4 ° celcius ( c ). plasma was then separated and stored at − 20 ° c . until analysis . plasma ( 0 . 5 ml ) was used to extract cgrp by addition of 0 . 8 ml of ethanol . the mixture was centrifuged at 1600 g for 20 minutes . after removing the supernatant , the extracted samples were air dried at room temperature overnight and then stored at 4 ° c . immediately prior to assay , dried samples were reconstituted with assay buffer following manufacturer &# 39 ; s instructions ( peninsula labs ) and assayed for cgrp by radioimmunoassay ( ria ). cgrp antiserum , code ras 6012 , was used . the dynamic assay range was 1 - 128 picograms ( pg ) per 300 microliters ( μl ) of sample . stimulation with hno / no − donors and diagnostic tests were performed as described above in example 1 . with reference to fig6 , administration of the selective cgrp antagonist cgrp 8 - 37 resulted in a modest negative inotropic effect during heart failure as measured by ees . this result was not unexpected given that cgrp is known positive inotrope . doggrell , expert opin . investig . drugs , 10 : 1131 - 8 ( 2001 ). more interestingly , cgrp 8 - 37 effectively prevented the hno / no − - mediated , positive inotropic effect of angeles salt as is illustrated by a comparison of the ees data resulting from the combined administration of cgrp 8 - 37 and angeli &# 39 ; s salt with the results observed from administration of angeli &# 39 ; s salt alone . these results illustrate that the positive inotropy of hno / no − is caused by stimulating release of cgrp , which is a nonadrenergic / noncholinergic ( nanc ) neuromodulator . this is supported by the data illustrated in fig7 , which show that blood plasma cgrp levels were increased by administration of the hno / no − donor angeli &# 39 ; s salt in both normal and heart failure conditions . a sensitive and specific radioimmunoassay ( ria ) was used to study blood plasma levels of cgrp in normal and in chf dogs , both in basal and stimulated conditions ( after administration of as , dea / no and nitroglycerin ). the basal mean plasma levels of cgrp were 23 , 24 . 5 and 27 pg / ml in the artery , vein , and coronary sinus of normal dogs , respectively . these levels were significantly reduced in all vascular compartments in chf dogs : 13 . 3 ± 0 . 7 , 14 . 3 ± 1 . 4 , and 14 ± 0 . 6 pg / ml in artery , vein , and sinus , respectively . when stimulated with the hno / no − donor as , plasma cgrp levels increased substantially in both normal and chf dogs ( fig7 ). in contrast , stimulation with dea / no and nitroglycerin failed to significantly increased cgrp levels . these data clearly show that hno / no − directly stimulates the release of cgrp . this example demonstrates that hno / no − effectively increases contractility even when administered to a subject receiving beta - antagonist therapy . as illustrated in fig8 , administration of the hno / no − donor angeli &# 39 ; s salt ( as described in example 1 ) to a normal subject that is receiving beta - antagonist therapy ( propranolol , 2 milligrams / kg in bolus ) caused an increase in contractility as indexed by ees and d edv . this increase was observed despite the propranolol - induced reduction in myocardial performance . similar results were obtained in one heart failure subject ( data not shown ). the above - described examples merely provide particular embodiments of the provided method . they are not intended to be limiting in any way . moreover , although embodiments of the method provided have been described herein in detail , it will be understood by those of skill in the art that variations may be made thereto without departing from the spirit of the invention or scope of the appended claims .
administration of an hno / no − donating compound , such as angeli &# 39 ; s salt , increases myocardial contractility while concomitantly lowering left ventricular preload in subjects experiencing heart failure . moreover , administration of the hno / no − donating compound isopropylamine / no 2 chnhnno ) surprisingly exhibited positive inotropic effects in subjects experiencing heart failure that were superior to those caused by the hno / no − donating compound angeli &# 39 ; s salt . additionally , in contrast to the effects observed with no donors , administration of an hno / no − donor in combination with a positive inotropic agent did not impair the positive inotropic effect of the positive inotropic agent . further , hno / no − exerts its positive inotropic effect independent of the adrenergic system , increasing contractility even in subjects receiving beta - antagonist therapy .