Occasional review Nitric oxide and lung disease

Even five years ago few could have realised that the simple gas nitric oxide (NO) would be involved in the regulation of so many physiological functions and pathophysiological processes. There has been an explosion of information about nitric oxide which appears to be involved in an extraordinary range of functions including vascular regulation, neurotransmission, host defence, and cytotoxicity.1 2 An increasing volume of literature has shown the importance of nitric oxide in the regulation of various pulmonary functions and suggested its involvement in several pulmonary diseases.34 The purpose of this review is to highlight some of the recent advances in this rapidly moving field. For over 20 years it has been recognised that the vasodilator responses to many agents are mediated by the release of a vasodilator substance from endothelial cells.5 The identity of endothelium derived relaxant factor (EDRF) remained elusive, largely because of its short half life, until 1987 when two groups independently suggested EDRF had the characteristics of nitric oxide.67 Many were surprised that such a simple molecule could account for all of the actions of EDRF, but extensive investigations in many species have now provided compelling supportive evidence.' Parallel investigations established that nitric oxide was also important in macrophage mediated cytotoxicity.89