Nitric oxide - chemical formula NO - is the first gas shown to act as a chemical messenger in the body, relaying information from nerves to cells that control a range of bodily functions, from digestion to sexual excitement.
Scientists have shown that tiny amounts of the gas are essential for the normal functions of the brain, arteries, immune system, liver, pancreas, uterus, nerves and lungs, to name but a few.
The American Association for the Advancement of Science, which organises the Molecule of the Year award, said that a decade ago nitric oxide was just another toxic chemical found in unsavoury haunts such as cigarette smoke and smog. 'Aside from the discovery of NO as the first gas to behave as a biological messenger molecule, scientists are amazed at the range of bodily activities it appears to influence.'
Scientists proved this year the gas is crucial in male erections. Key pelvic nerves get a message from the brain and make nitric oxide, which dilates blood vessels, 'blood rushes in, and the penis rises to the occasion.'