Vascular nitric oxide: effects of physical activity, importance for health.

NO (nitric oxide), formed in the vascular endothelium and derived from a biochemical reaction catalysed by eNOS (endothelial NO synthase), appears to play a role in exercise-induced dilation of blood vessels supplying cardiac and skeletal muscle. Endothelium-dependent, NO-mediated vasodilation is augmented by exercise training. Increases in eNOS gene transcription, eNOS mRNA stability and eNOS protein translation appear to contribute to increased NO formation and, consequently, enhanced NO-mediated vasodilation after training. Enhanced endothelial NO formation may also have a role(s) in the prevention and management of atherosclerosis because several steps in the atherosclerotic disease process are inhibited by NO. A growing body of work suggests that exercise training, perhaps via increased capacity for NO formation, retards atherosclerosis. This has significant implications for human health, given that atherosclerosis is the leading killer in Western society.