UCLA MEDICAL SCHOOL TEACHER WINS NOBEL; IGNARRO'S RESEARCH ON NITRIC OXIDE LED TO DEVELOPMENT OF VIAGRA.

Byline: David R. Baker Daily News Staff Writer

When his colleagues at UCLA tracked down Louis J. Ignarro in France early Monday to tell him he'd won the Nobel Prize, he thought they were joking.

``He said, `Don't play pranks on me.' I think it's going to take some time to sink in,'' said Gautam Chaudhuri, one of Ignarro's friends and collaborators at the University of California, Los Angeles.

Ignarro, a Malibu resident, was one of three American researchers named Monday for the Nobel Prize in medicine for their work identifying the role of nitric oxide in the body. His study of the compound, which relaxes blood vessels, helped pave the way for the anti-impotence drug, Viagra.

``From tomorrow on, my life won't be changed, but my devotion to research will be redoubled,'' said Ignarro, who had been en route to a scientific conference in Naples, Italy, when he heard the news.

Dr. Gerald Levey, dean of the UCLA School of Medicine, praised him as an outstanding teacher and researcher. Ignarro is a 10-time winner of the school's Golden Apple Award, given by medical students to their favorite professors.

``He has a great scientific mind,'' said Levey. ``In some ways it's not surprising that a great teacher and a great scientist go hand in hand.''

Levey was awakened with the news at 3 a.m. Monday. Ignarro's wife, a UCLA resident in anesthesiology, got the call about 30 minutes later.

``I'm very proud of him,'' she said, fielding hugs from colleagues outside her husband's lab. ``I certainly always felt he deserved it.''

Ignarro shares the $978,000 prize with Robert F. Furchgott, a pharmacologist at the State University of New York in Brooklyn, and Ferid Murad of the University of Texas Medical School in Houston.

Ignarro has devoted much of his career to studying nitric oxide. The gas plays several important roles in the body, regulating blood pressure, preventing blood clots and killing invading or cancerous cells.

``It affects the nervous system, the immune system. It's everywhere,'' said Georgette Buga, who has worked with Ignarro since 1986.

In 1986, Ignarro suggested that a substance researchers were calling ``endothelium-derived relaxing factor,'' which Furchgott had first described, was most likely nitric oxide. Ignarro and Chaudhuri together showed that EDRF was definitely nitric oxide.

Ignarro later became the first to show that penile erections are dependent on nitric oxide, research which was central to recent development of Viagra for impotence.

Although UCLA faculty members won four previous Nobel Prizes, Ignarro is the first from the School of Medicine to win one.

The Associated Press contributed to this story.