Effects of propafenone on function and metabolism in the ischemic working rat heart.

We examined the effects of propafenone, a new anti-dysrhythmic agent, on myocardial function and metabolism in ischemic working rat heart preparations. In the treated hearts, propafenone, 0.3 micrograms/ml and 3 micrograms/ml, were added to Krebs-Henseleit bicarbonate buffer perfusate throughout the experiments. Whole heart ischemia was induced through a one-way aortic valve for 15 min followed by 'reperfusion for 30 min. After induction of ischemia, the cardiac output, peak aortic systolic pressure, left ventricular dP/dtmax, and myocardial ATP concentration were greater in the treated hearts than in the untreated ones. All hearts in the untreated group developed ventricular fibrillation (Vf) at the beginning of the reperfusion period. On the other hand, no treated hearts had Vf at any time during the experiment. However, propafenone, 3 micrograms/ml, evoked a negative inotropic effect before and after ischemia. These results indicate that propafenone may contribute to early recovery from ischemia in myocardial function and metabolism, although it has a negative inotropic action.