Antiarrhythmic effects of the thromboxane antagonist BM 13.177

The effects of the thromboxane antagonist BM 13.177 (5 mg kg-1 + 0.15 mg kg-1 min-1) was investigated on the ventricular arrhythmias that result from coronary artery occlusion and reperfusion in anaesthetised open-chest greyhounds. BM 13.177 markedly reduced the severity and incidence of arrhythmias resulting from ischaemia; the number of ventricular ectopic beats was reduced from 1,084 +/- 159 (in controls) to 544 +/- 179 (in dogs given BM 13.177) and the incidences of ventricular tachycardia (VT) and ventricular fibrillation (VF) were reduced from 86 to 22% and from 30 to 10% respectively. Following reperfusion the incidence of VF was 86% in controls and 44% in dogs given BM 13.177. Thus the total incidence of VF during the combined ischaemia-reperfusion insult was significantly reduced by treatment with BM 13.177 from 90% (in control dogs) to 50%. These results lend further support to the hypothesis that thromboxane is involved in the genesis of arrhythmias and that blockade of thromboxane receptors may be a suitable approach to antiarrhythmic therapy under conditions of ischaemia and reperfusion.