Enhanced nitric oxide-mediated vascular relaxation in radial artery compared with internal mammary artery or saphenous vein

The superior long-term patency of internal mammary artery coronary bypass grafts compared with venous grafts has been attributed in part to increased endothelium-derived nitric oxide (. NO) production. Interest in the radial artery as an alternative bypass conduit has recently been revived; however, its biological characteristics remain incompletely defined. The purpose of this study was to compare the.NO-mediated vasomotor properties of the radial artery to those of the internal mammary artery and saphenous vein. Matched segments of radial artery, internal mammary artery, and saphenous vein (n=24 patients) were examined by use of organ-chamber methodology. Endothelium-dependent and -independent vasomotor responses were assessed by dose-response curves to acetylcholine, N(G)-nitro-L-arginine methyl ester (L-NAME), 8-bromo-cyclic 3',5'-guanosine monophosphate (8-bromo-cGMP), and nitroglycerin. Maximum.NO-mediated radial artery relaxation in response to acetylcholine (86+/-10%) was significantly greater than internal mammary artery (56+/-9%) or saphenous vein (11+/-5%, both P