Effects of Thromboxane Synthetase Inhibitors on Cyclical Reduction of Coronary Blood Flow in Dogs

Abstract

Effects of new inhibitors of thromboxane synthetase, (E)-3-[(1-imidazolmethyl)phenyl]-2-propenoic acid and (E)-3-[4-(pyridylmethyl) phenyl]-2-methyl-2-propenoic acid on cyclical reduction of flow in the partially constricted coronary artery were examined in anesthetized beagle dogs. Intravenous injections of both agents with a dose of 20mg/Kg eliminated the cyclical reduction induced by constriction in the majority of experiments. However, they failed to eliminate the cyclical reduction induced by indomethacin. Indomethacin-induced reduction was eliminated by prostaglandin I₂ in all experiments. It is suggested that thromboxane A₂ acted as an accelerator in the cyclical reduction of coronary flow induced by coronary constriction, but did not in the reduction induced by indomethacin