Nitric oxide, the gas in the news

Nitric Oxide(NO), a small molecule and a water-soluble gas, is formed in traces in several animal tissues. Its arrival on the biological scene was heralded by the magazine,Science as the “molecule of 1992”. It is biologically active as a signal molecule in relaxing contracted smooth muscle. Furchgott, Ignarro and Murad were awarded the Nobel Prize in Medicine or Physiology in 1998 for discovering this effect. Convergence of three independent lines of investigation led to recognition of vital roles of NO in cellular function-relaxation of smooth muscle tissue, cytotoxic function in macrophages, and transmission of signals in brain cells. The performance of NO in these three major physiological roles will be briefly described here. It will become obvious that NO can be a saviour, a killer or a messenger.