The biological significance of nitric oxide formation from L-arginine.

The vascular endothelium synthesizes nitric oxide (NO) from the terminal guanidino nitrogen atom( s) of L-arginine. NO accounts for the biological actions of endotheliumderived relaxing factor (EDRF). It is becoming apparent that the synthesis of NO from L-arginine not only explains endothelium-dependent vascular relaxation, but is a widespread mechanism for the regulation of cell function and communication. The evidence for this so far derives from work on vascular endothelial cells, macrophages, the central nervous system and neutrophils, although it is likely that this mechanism is also present in other tissues. This review will outline the evidence for this hypothesis and will consider its physiological and pathological implications.