Effect of sildenafil on coronary active and reactive hyperemia

Division of Cardiology, Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota 55455 Sildenafil, a selective inhibitor of phosphodiesterase type 5, produces relaxation of isolated epicardial coronary artery segments by causing accumulation of cGMP. Because shear-induced nitric oxide-dependent vasodilation is mediated by cGMP, this study was performed to determine whether sildenafil would augment the coronary resistance vessel dilation that occurs during the high-flow states of exercise or reactive hyperemia. In chronically instrumented dogs, sildenafil (2 mg/kg per os) augmented the vasodilator response to acetylcholine, with a leftward shift of the dose-response curve relating coronary flow to acetylcholine dose. Sildenafil caused a 6.7 ± 2.1 mmHg decrease of mean aortic pressure, which was similar at rest and during treadmill exercise ( P