Antiarrhythmic and antinecrotic effects of yohimbine stereoisomers in rats during coronary occlusion and reperfusion.

In pentobarbital-anesthetized rats the left coronary artery was ligated for 5 or 30 min and then opened for reperfusion of the ischemic myocardial area. Twelve min prior to the coronary occlusion yohimbine stereoisomers, namely corynanthine and rauwolscine, or saline solution were given intravenously. In the saline controls both ischemia and reperfusion provoked severe tachyarrhythmias with ventricular fibrillation in 37.5% or 54.6%, respectively. Using corynanthine and rauwolscine a highly significant antiarrhythmic effect was observed. Corynanthine completely prevented ventricular fibrillation and delayed significantly the development of myocardial necrosis. The factors likely underlying the antiarrhythmic and antinecrotic effects are discussed.