Since the first description of the "endothelium-derived relaxing factor" (EDRF) in 1980 the function of the endothelium has developed into a field of research of its own. The most important endothelial factor is nitric oxide (NO), which is formed from l-arginine with the help of NO synthase (NOS). Disturbances of the endothelial function play an important role in men's health such as atherogenesis and erectile dysfunction and are also followed by morphological vessel changes. Furthermore, NO seems to play an important role in LUTS (lower urinary tract symptoms) and male fertility.
