Oral l-arginine improves endothelium-dependent dilatation and reduces monocyte adhesion to endothelial cells in young men with coronary artery disease

l-Arginine is the physiological substrate for nitric oxide synthesis by the vascular endothelium. In hypercholesterolaemic rabbits, oral l-arginine reduces atheroma, improves endothelium-dependent dilatation and reduces monocyte/endothelial cell adhesion. The effect of oral l-arginine on endothelial physiology is unknown, however, in humans with established atherosclerosis. In a prospective, double-blind, randomised crossover trial, ten men aged 41±2 years with angiographically proven coronary atherosclerosis took l-arginine (7 g three times per day) or placebo for 3 days each, with a washout period of 10 days. After l-arginine, compared to placebo, plasma levels of arginine were increased (318±18 vs. 124±9 μmol/l, P