[Effects of sophoramine on ventricular fibrillation threshold and dispersion of refractoriness in cats].

A decrease in the ventricular fibrillation threshold (VFT) was found to be negatively correlated with an increase in the dispersion of refractoriness (DR) during myocardial ischemia or infarction. Sophoramine (Sop) increased the VFT of normal and ischemic cat hearts. and decreased ventricular tachyarrhythmias induced by programmed electric stimulation and the spontaneous development of VF. The mechanism was believed to be related to the facts that Sop increases the effective refractory periods, decreases DR and reduces the size of the myocardial infarction (MI). The chronically infarcted cat heart appears to be a reliable model for studying the vulnerability to VF after MI.