Ignarro, Louis J(oseph) (1941– )

US pharmacologist who with US pharmacologists Robert F Furchgott and Ferid Murad was awarded the Nobel Prize for Physiology or Medicine in 1998 for the discovery that nitric oxide acts as a signalling molecule in the cardiovascular system.

In 1980, Robert F Furchgott discovered that the cells of the inner lining of a blood vessel could produce a substance that caused blood vessels to dilate. He called this unknown substance endothelium-derived relaxing factor (EDRF) after the name given to the inner lining of the blood vessel, the endothelium. Working independently from Furchgott, Ignarro identified EDRF as the gas nitric oxide (NO) and published his results in 1986. This was the first time that a gas had been recognised as a signal molecule and stimulated an enormous interest in NO research. This discovery is of significant important in medicine and could provide insights into the treatment of heart disease, shock, and cancer. A direct result of this discovery has been the development of the anti-impotence drug, sildenafil citrate, which is marketed under the trade name Viagra.

Ignarro was born in Brooklyn, New York, USA. He received his PhD from the University of Minnesota in 1966. He was appointed professor of pharmacology at Tulane University, New Orleans, in 1979 and retained this position until 1985 when he became a professor of pharmacology at the University of California, Los Angeles.