The vasodilator effect of coronary vascular endothelium in situ: its inactivation by hydroquinone.

Studies were carried out to demonstrate the presence of the endothelium derived relaxing factor (EDRF) in coronary arteries in situ and the effect of hydroquinone on this factor. The studies revealed the presence of EDRF in coronary arteries of rabbit hearts remaining in situ. EDRF was inactivated by left atrial injection of hydroquinone. In situ constriction of coronary arteries by vasopressin was markedly increased following exposure to hydroquinone, and the dilatory response to acetylcholine was absent. The experiments confirm the presence of the endothelium derived relaxing factor in coronary arteries in situ and its inactivation by hydroquinone.