Using microsensors, it is possible to quantify the amount and concentration of nitric oxide (NO) release throughout the cardiovascular system in veins, arteries and the heart. Under normal physiological conditions a well defined distribution of NO is maintained. This concentration depends++ on the laminar, turbulent, or pulsatile flow rate of blood. Significantly reduced production of NO is observed in the pathogenesis of cardiovascular disorders like hypertension, atherosclerosis and diabetes. This is due to increased generation of superoxide by a dysfunctional endothelium and the rapid formation of peroxynitrite followed by formation of peroxynitrite followed by the formation of highly reactive OH and NO2 radicals and NO2+. Elevated concentration or improved mass transport of L-arginine and (6)-5,6,7,8-tetrahydrobiopterin can be applied to increase/decrease NO/superoxide release by the dysfunctional endothelium.