Enhanced Nitric Oxide-Mediated Vascular Relaxation in Radial Artery Compared With Internal Mammary Artery or Saphenous Vein

Publisher Website
Google Scholar
Abstract
Background—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. Methods and Results—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, NG-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 PPP50=33±7 nmol/L) than the internal mammary artery (203±32 nmol/L) or saphenous vein (97±12 nmol/L, both PPConclusions—These data indicate that ·NO-dependent relaxation of radial artery is greater than that of internal mammary artery or saphenous vein. This difference is related to endothelial production of ·NO and/or vessel sensitivity to ·NO. Such favorable physiological characteristics of radial artery could conceivably contribute to improved long-term patency of this conduit compared with saphenous vein.