Nitric oxide: a new biological messenger molecule.

Nitric oxide, a recently discovered gaseous biological messenger molecule, has been found to play a fundamental regulatory role in the body. It is involved in the cardiovascular, immune, reproductive, and digestive physiology and its presence in the brain indicates that it will have a neuronal function as well. Several areas of research suggest that low levels or absence of nitric oxide may be the underlying cause of some forms of essential hypertension and impotence, while over-production could be the cause of neuronal damage, septic shock, and immune-related tissue damage.