Nitric oxide helps high-altitude survival

CLEVELAND, Nov. 6 (UPI) -- U.S. researchers have discovered high blood levels of nitric oxide allow people to live at high altitudes where air has low levels of oxygen.

Dr. Serpil Erzurum, chairman of the Cleveland Clinic’s Department of Pathobiology, and colleagues from Case Western Reserve University analyzed blood samples and blood flow readings from 88 Tibetans living at altitudes of 14,000 feet. They compared the measurements with those of 50 people who live at locations near sea level.

The Tibetans were found to have 10 times more nitric oxide and more than double the forearm blood flow of sea-level dwellers.

The researchers said they believe the high levels of nitric oxide cause an increased blood flow that provides body tissues with sufficient amounts of oxygen despite low levels of oxygen in both the air and the bloodstream.

The study is reported in the Proceedings of the National Academy of Sciences.