Figure 1.

Scheme of nitric oxide (NO) synthesis MAPK activation in myeloid or glial cells can trigger NF-κB transcriptional activation, leading to expression of iNOS. iNOS is subsequently transformed to NOS, which in the presence of NADPH converts L-arginine to L-citrulline and free NO radicals. Stimulants such as bradykinin, acetylcholine, histamine, leukotrienes, and platelet-activating factors from neuronal/endothelial cells or other origins can induce expression of eNOS, and nNOS converts L-arginine to free NO radicals through the same oxidation process.