This year's Nobel Prize for Physiology or Medicine has been awarded to three US pharmacologists for their discovery that the unstable gas, nitric oxide (NO), is an essential regulator of vasodilation.

Ferid Murad

Working independently, Robert F. Furchgott, 82 (State University of New York, Brooklyn) and Louis J. Ignarro, 57 (University of California, Los Angeles), concluded in 1986 that NO is the factor released by endothelial cells that induces relaxation of blood vessel smooth muscle. Ferid Murad, 62 (University of Texas Medical School, Houston) discovered that the gas activates the cyclic GMP signal transduction pathway and that the vasodilator nitroglycerin ameliorates heart attacks by promoting NO release. Furchgott and Murad shared the 1996 Albert Lasker Award for Basic Medical Research, which is often considered a predictor of future Nobel Prize winners.

In addition to NO's importance in vasodilation, it also acts as a neurotransmitter in the central nervous system and is used by macrophages to kill bacteria and tumor cells. Drugs that regulate NO release are under development for the treatment of heart disease, high blood pressure, cancer and toxic shock syndrome. The anti-impotence drug Viagra promotes NO-induced vasodilation of penile blood vessels by preventing breakdown of cyclic GMP.

Robert Furchgott

A delighted Furchgott, who still works on blood vessel biology in the laboratory, told Nature Medicine he has only one regret, "I feel that the Nobel Prize Committee could have made an exception this year and chosen a fourth person, Salvador Moncada, [to share the prize]."

Whereas it had been predicted that NO's crucial role in many physiological processes would earn its discoverers the coveted prize, the awarding of the Nobel Memorial Prize in Economic Science to Amartya Sen, Master of Trinity College, Cambridge, and an expert in welfare economics was unexpected. Sen is credited with changing how international organizations and governments respond to poverty and famine.

Louis Ignarro