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The effect of sildenafil on human vascular function, platelet activation, and myocardial ischemia

Julian P. J. Halcox, MA, MRCP^*, Khaled R. A. Nour, MD^*, Gloria Zalos, RN^*, Rita Mincemoyer, RN^*, Myron A. Waclawiw, PhD^*, Candido E. Rivera, MD, Georgia Willie, MD, Samer Ellahham, MD and Arshed A. Quyyumi, MD, FRCP, FACC^*,*

^* National Heart, Lung, and Blood Institute, Bethesda, Maryland, USA
Department of Hematology, National Institutes of Health, Bethesda, Maryland, USA
Department of Cardiology, Washington Hospital Center, Washington, DC, USA

View larger version (14K): [in a new window]   Figure 1 Effect of sildenafil (100 mg PO) on epicardial coronary diameter in all patients and the subsets with and without coronary atherosclerosis (CAD).

View larger version (14K): [in a new window]   Figure 2 Effect of sildenafil on percent of change in epicardial coronary artery diameter in segments that were initially constricted with acetylcholine (denoting endothelial dysfunction) and those that were initially dilated with acetylcholine (preserved endothelial function).

View larger version (22K): [in a new window]   Figure 3 Effect of sildenafil on microvascular vasodilation (percent of change in coronary vascular resistance [CVR] as a result of acetylcholine and verapamil in all patients and in response to acetylcholine in patients with and without angiographic coronary atherosclerosis (CAD).

View larger version (9K): [in a new window]   Figure 4 (A) Effect of sildenafil on epicardial coronary artery diameter ratio cold-pressor testing (CPT)/verapamil. (B) Effect of sildenafil on microvascular vasodilation (reduction in coronary vascular resistance) during CPT. Black bars = pre-sildenafil; white bars = post-sildenafil.

View larger version (16K): [in a new window]   Figure 5 Effect of sildenafil on surface expression of activated platelet glycoprotein IIb/IIIa receptors illustrated by the percentage of platelets binding FITC-conjugated PAC-1 antibodies. ADP = adenosine diphosphate; TRAP = thrombin receptor activator peptide. Black bars = pre-sildenafil; white bars = post-sildenafil. *p < 0.05, **p < 0.01, NS = not significant.

View larger version (13K): [in a new window]   Figure 6 Flow-mediated vasodilation (percent of change in diameter of the brachial artery compared with baseline) is shown during hyperemia, before and after sildenafil. Filled circles = pre-sildenafil; open circles = post-sildenafil.*p < 0.05 pre- vs. post-sildenafil.