INFLUENCE OF ENDOTHELIN-1 ON VENTRICULAR- FIBRILLATION THRESHOLD IN ACUTE MYOCARDIAL ISCHEMIC RATS

The influence of endothelin-1 on ventricular fibrillation threshold wa s studied in acute myocardial ischemic rats. Endothelin-1 (1.5 - 3.0 m u g.kg(-1) iv) given 5 min before ischemia reduced the ventricular fib rillation threshold in a dose- and time-dependent manner. Its effect l asted at least 60 min. marked increase of spontaneous ventricular tach ycardia and myocardial infarct size was seen and the arterial blood pr essure was at a higher level (18.5 - 20.1/14.4 - 15.8 kPa) after 3.0 m u g.kg(-1). Diltiazem prevented par- tially from reduction of ventricu lar fibrillation threshold, eliminated completely the vasopressor resp onse and limited the extension of myocardial necrosis induced by endot helin-1.