Effects of captopril and lisinopril on the coronary resistance in the rabbit isolated heart

Abstract

The effect of bolus injections of the two angiotensin-converting enzyme inhibitors (ACEI); captopril (46 nmol), having a sul-phydryl moeity in structure and Iisinopril (25 nmol), without a sulphydryl group; on the coronary microvasculature of isolated rabbit hearts perfused with constant flow was investigated. Results show that ACEIs possess coronary vasodilator effect, independent of concentration. The relaxant response to ACEIs is not abolished by methylene blue (1pM), an inhibitor of basal release of endothelium-derived relaxing factor (EDRF). This study has revealed that in isolated perfused rabbit heart, captopril and Iisinopril induce a vasodilator action that is not mediated via EDRF release.