Effects of alcohol on isoproterenol-induced ventricular fibrillation in adult rats.

To determine whether the pattern of alcohol consumption, intake, and withdrawal modulates the incidence of malignant ventricular arrhythmias and sudden cardiac death due to beta-adrenergic stimulation in a species susceptible to administration of isoproterenol alone, a regimen was formulated in which both continuous and interrupted alcohol ingestion was obtained. After alcohol treatment of fully mature, adult rats for 7 weeks, a single subcutaneous injection of 150 micrograms/kg of isoproterenol was given to control (non-alcohol-treated), alcoholic (continuous consumption), and alcohol withdrawal (interrupted) rats. The incidences of malignant ventricular arrhythmias and related deaths were compared. The results revealed that arrhythmias and arrhythmic deaths were highest in the "alcohol withdrawal group," 92% and 54%, respectively. As judged from baseline studies, withdrawal of alcohol produced a 16% decrease in serum K+ concentration compared with controls, whereas continuous alcohol ingestion resulted in a 20% elevation in magnesium concentration. These electrolyte changes were further affected by isoproterenol and may have contributed to the differential response to beta-adrenergic stimulation as a result of the pattern of alcohol intake.