Effect of EDRF release from freshly harvested endothelial cells on the coronary circulation of the isolated working rabbit heart.

Vascular relaxation in rabbit aortic preparations by acetylcholine is endothelium-dependent. Because of the short half-life of the endothelium-derived relaxing factor(s) (EDRF), a constant source of this material is necessary to study its effect in perfused hearts or hearts in situ (reported half-life 6-50 sec). To investigate the effect of EDRF(s) on the large coronary arteries and the resistance vessels of the isolated working rabbit heart, freshly harvested porcine endothelial cells were used. The cells were stimulated with acetylcholine to produce EDRF(s). To extend the half-life of EDRF, superoxide dismutase was added to the cell suspension. Left atrial infusion of these cells increased coronary flow and reduced total coronary resistance. No significant effect on the diameter of the endothelium-deprived obtuse marginal coronary artery was noted. The vasoconstrictor effect on resistance vessels of topically applied histamine was significantly reduced during the infusion of activated endothelial cells. It can be concluded that EDRF(s) released from freshly harvested endothelial cells increases coronary flow and diminishes total coronary vascular resistance in the working heart. In this preparation coronary arterioles are more sensitive to EDRF(s) than large coronary arteries. EDRF may contribute to the regulation of regional myocardial flow.