New York (PTI) Robert F Furchgott, a Nobel prize-winning pharmacologist who helped lead to the development of Viagra, the anti-impotency drug, died in Seattle.

He was 92. His daughter Susan Furchgott confirmed the death, The New York Times reported.

Furchgott's work with the gas nitric oxide opened new vistas of research in cardiovascular functions.

Nitric oxide had been known as an air pollutant that contributed to smog and acid rain, but research by Dr.Furchgott and others have proved that it acted as an important signal in the cardiovascular system, mediating blood pressure and blood flow.

In awarding the prize for physiology or medicine in 1998, the Swedish Nobel assembly praised the scientists for providing the first proof that a gas, despite its inherent instability and ephemeral nature, can perform important biochemical functions in the body.

Research has indicated that nitric oxide, a colourless, odourless gas, has significant medical potential.

In the 1950s, Furchgott developed a method for determining how blood vessels respond to medications, neurotransmitters and hormones, using a rabbit’s artery.

Another early contribution was his discovery that such muscles relax when exposed to ultraviolet light, a phenomenon known as photo-relaxation.