ANTIARRHYTHMIC AND MYOCARDIAL METABOLIC EFFECTS OF VERAPAMIL DURING CORONARY ARTERIAL REPERFUSION. A. Kobayashi, Y. Suzuki, Y. Masumura, H. Hayashi, M. Abe, K. Nishihara, T. Kamikawa, N. Yamazaki. Third Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan To determine the effects of verapamil(VP) on ventricular fibrillation(Vf) and free fatty acids(FFA) metabolism during coronary arterial occlusion for 40 min and reperfusion for 15 min. VP(O.lmg/kg) was administered in 5 min before occlusion and followed by an infusion of O.Olmg/kg /min during examination.ECGs were recorded throughout the experiment.Myocardial samples were obtained from both the ischemic and nonischemic zones after reperfusion and meas ured ATP,free carnitine(FC),long chain acyl carnitine(LC) ,long chain acyl CoA and FFA.VP significantly reduced the incidence rate of Vf. ATP and FC levels in the ischemic zone in the VP group were significantly higher than those in the control. LC levels in both the ischemic and nonischemic zones in the VP group were significantly lower. This suggests that VP has protective effects on Vf and on FFA metabolic changes after coronary arterial reperfusion