Anti-arrhythmic and electrophysiological effects of the endothelin receptor antagonists, BQ-123 and PD161721

The effects of the endothelin ET A, (BQ-123) and endothelin ET A/B (PD161721) receptor antagonists were investigated on ischaemia-induced arrhythmias and on the maximum following frequency. The study was carried out in Langendorff perfused rat hearts subjected to coronary artery occlusion in which the severity of arrhythmias, coronary perfusion pressure and heart rate were measured. The % incidence of ischaemia-induced irreversible ventricular fibrillation (ventricular fibrillation) was reduced significantly from 58%, in control rat hearts, to 0% (at 10 −7 and 10 −6 M PD161721 and 10 −6 M BQ-123 P