Louis J. Ignarro, Professor of pharmacology at the University of California School of Medicine at Los Angeles, shared with Robert F. Furchgott and Ferid Murad the 1998 Nobel Prize in physiology or medicine for their contributions to the discovery of endogenous nitric oxide gas in complex organisms and its physiological implications. Nitric Oxide (NO) was, until recently, known as a common air pollutant and for its presence in body tissues as the result of nitroglycerin metabolization, as found by Ferid Murad in 1977. Murad and his group also reported that nitric oxide and other nitro compounds activated the enzyme guanylate cyclase in the cytosol, causing the elevation of cyclic GMP levels in several tissues. Ignarro's studies of cyclic GMP and NO had shown in 1979 that nitric oxide gas promotes the conversion of GTP to cyclic GMP and pyrophosphate, thus acting as a relaxant of the smooth muscle of blood vessels...