What is nitric oxide and why are so many people studying it?

From social outcast to citizen of the year in less than a decade is the stuff of fiction. That is precisely what has happened, however, to a remarkably simple molecule, nitric oxide. Nitric oxide is still an environmental pollutant, suspected carcinogen, and precursor of acid rain, but biologists are looking past its dark side. They now see a molecule that is uniting neuroscience, physiology, and immunology. Its ubiquitous distribution in the body and its multifaceted roles are revising our understanding of how cells communicate and protect themselves. This report examines nitric oxide's role in physiology and pathophysiology and reviews novel therapeutic approaches which involve inhibition or induction of the activity of endogenous nitric oxide.