Time course of epinephrine-induced arrhythmias in cats exposed to dichlorodifluoromethane

Abstract

Inhalation of high concentrations of aerosol propellants, e.g., CCl 2F 2, is known to cause sudden death in man, sometimes minutes after the end of exposure, and to sensitize dogs to severe epinephrine-evoked ventricular tachyarrhythmias. To assess the duration and the rate of disappearance of myocardial sensitization, we injected 13 pentobarbital-anesthetized cats iv with 4 or 8 μg/kg epinephrine before, and at 3, 5, 8 and 10 min after, a 4-min inhalation of a 37% CCl 2F 2-21% O 2-42% N 2 mixture. Electrocardiograms and intraarterial pressures were recorded, and concentrations of CCl 2F 2 in arterial blood were measured by gas chromatography. Before exposure to CCl 2F 2, no cats had epinephrine-evoked ventricular tachyarrhythmias. After CCl 2F 2 inhalation, each cat developed epinephrine-evoked ventricular tachyarrhythmias. The CCl 2F 2-induced susceptibility to epinephrine-evoked ventricular tachyarrhythmias remained after the end of CCl 2F 2 inhalation, varying inversely with time and occasionally persisting as long as 10 min post CCl 2F 2 inhalation.