Fortnightly Review Biology and clinical relevance of nitric oxide

Ten years ago the idea that nitric oxide might be a biological mediator would have seemed far fetched.Clinicians might have recalled from schooldays that nitric oxide is a clear, colourless gas which rapidly turns brown on contact with air, anaesthetists might have remembered the series of disasters related to inadvertent contamination of cylinders of nitrous oxide with nitric oxide, the environmentally aware would have been familiar with the gas as a product of car exhaust and cigarette smoke and as a pollutant, and for others it would have conjured up images of primordial swamps and electrochemical storms.However, in 1987 it was shown that mammalian cells synthesise nitric oxide, a year later it was suggested that cells communicate with each other by the synthesis of nitric oxide from the amino acid arginine,' and in 1993 there were over 1000 publications on the biology of nitric oxide.This improbable biological mediator has been implicated in the pathogenesis of diseases ranging from hypertension to septic shock and dementia.'