[Effect of isoptin on toxic and cardiotonic effect of strophanthin K].

Two models of heart failure were used in rat experiments to study the effect of isoptin on tolerance to the toxic effect of k-strophanthin. Calcium antagonist-induced changes in the cardiotonic and chronotropic effects of the cardiac glycoside and myocardial oxygen consumption were examined in isolated frog atria with a movable-electrode electron tube and polarography. Isoptin was shown to substantially enhance tolerance to the toxic effect of k-strophanthin and slightly decrease positive inotropic effects of the cardiotonic, by slowing down its development rate. The agent potentiated the negative chronotropic action and lowered myocardial oxygen consumption.