Influence of Ketanserin on Regional Myocardial Blood Flow After Myocardial Infarction in Baboons

Abstract

Serotonin (5-hydroxytryptamine, 5-HT) mediates vasoconstriction and vasodilation in normal coronary circulation of various animal species. In the presence of coronary artery disease, serotonin may inhibit coronary collateral formation and stimulate predominantly vasoconstriction. We tested the effect of ketanserin, a selective 5-HT2 receptor antagonist and platelet aggregation inhibitor, on ischemic myocardium blood flow (BF) and collateral formation after coronary artery occlusion in primates. Fifteen baboons were subjected to left anterior descending coronary artery (LAD) ligation and thrombus formation. Hemodynamics and regional myocardial blood flow (RMBF) (microsphere technique) were measured before and 45 min and 1 week after coronary artery occlusion. There was no significant difference in the hemodynamic measurements, gross infarct size, or infarct-ischemic zone MBF in the experimental group (ketanserin 1 mg/kg daily, n = 9) as compared with the control group (injectable water, n = 6). Both groups had a significant increase in BF ratio of infarct-ischemic/normal myocardium at 1 week as compared with shortly after coronary occlusion. Thus, selective 5-HT2 receptor blockade has neither an adverse nor a protective effect on myocardial infarct resulting from acute thrombotic coronary occlusion in baboons.