Effect of nifedipine on bronchomotor tone and histamine reactivity in asthma.
it is difficult to explain how successful resuscitation is possible after 40 minutes' submersion.2 The reduced oxygen requirement in profound hypothermia has been suggested by some authors as the mechanism by which tissue viability is maintained in these circumstances ,2 but this alone is an incomplete explanation, as for the submerged body to cool to a degree at which oxygen requirements are sufficiently reduced, heat transfer by mass flow-that is, circulation-must be present (a dead body cools relatively slowly). The degree of cooling encountered in our cases can be explained only by the fact that circulation was maintained for some or all of the period of submersion. The persistence of cardiac activity during such a prolonged period of apnoea supports the hypothesis that some protective mechanism may be present. We do not know whether ventricular fibrillation was present before resuscitative efforts were started and must concede that these efforts alone may have initiated the arrhythmia. Our cases show yet again that successful resuscitation is possible after long periods of immersion and emphasise the importance of performing electrocardiography early in the immersion incident, preferably at the accident site, before death is pronounced. 'Modell JH. The pathophysiology and treatment of drowning and near-Survival after 40 minutes sub-mersion without cerebral sequelae. Effect of nifedipine on bronchomotor tone and histamine reactivity in asthma Secretion of chenmical mediators from mast cells and contraction of bronchial smooth muscle are two major components in the patho-genesis of asthma. Both processes depend on the transmembrane passage of calcium ions, and drugs that inhibit this might therefore be expected to be of value in asthma. Cinnarizine, an antagonist to calcium transport, has been shown to exert a beneficial effect in patients with chronic asthma,' and verapamil, another calcium antagonist, prevents potassium-and serotonin-induced contraction of canine trachealis muscle.2 Nifedipine is a potent inhibitor of trans-membrane calcium ion flux, and results of a recent study suggest that .~~~~~~~~~~~~~~~~ it prevents exercise-induced asthma.3 We therefore investigated the effect of nifedipine on resting bronchomotor tone and on histamine reactivity in patients with asthma. We studied 10 patients, aged 25-60 years, with chronic stable asthma. The protocol was approved by the hospital research ethics committee, and all subjects gave informed consent. Each subject received either nifedipine 20 mg or placebo in a randomised double-blind fashion on separate days and was instructed to bite the capsules and keep the fluid in the mouth as long …