Tonal nitric oxide and health--a free radical and a scavenger of free radicals.

Basal/tonal nitric oxide (NO) production helps maintain particular microenvironments, i.e., vascular. Besides NO's function in controlling the activation state of various tissues such as immune cells, its presence appears to modulate other free radical levels, i.e., H2O2, in these same tissues and indeed these processes may be one and the same. Thus, by being a free radical, along with the ability to scavenge other free radicals, NO is placed in a pivotal regulatory position. We surmise that in the absence of adequate NO release other free radicals may go 'unchecked' and, therefore, initiate tissue damage. Furthermore, under these circumstances, proinflammatory events will occur due to heightened cell sensitivity and a diminished control of NF-kappaB. In an excess situation, and one without an appropriate circumstance, i.e., microbial action, NO may become the harmful agent. Hence, balancing basal NO production in body compartments may represent a fundamental process in maintaining general, long-term health.