Higher blood flow and circulating NO products offset high-altitude hypoxia among Tibetans

• DOI: 10.1073/pnas.0707462104
• Publication Date: 2007-10-31T03:33:20Z
• Authors: S. C. Erzurum; S. Ghosh; A. J. Janocha; W. Xu; S. Bauer; N. S. Bryan; J. Tejero; C. Hemann; R. Hille; D. J. Stuehr; M. Feelisch; C. M. Beall
• Keywords: Hypoxia

The low barometric pressure at high altitude causes lower arterial oxygen content among Tibetan highlanders, who maintain normal levels of use as indicated by basal and maximal consumption that are consistent with sea level predictions. This study tested the hypothesis Tibetans resident 4,200 m offset physiological hypoxia achieve delivery means higher blood flow enabled bioactive forms NO, main endothelial factor regulating vascular resistance. natural experimental design compared U.S. residents 206 m. Eighty-eight 50 volunteers (18-56 years age, healthy, nonsmoking, nonhypertensive, not pregnant, pulmonary function) participated. Forearm flow, an indicator systemic was measured noninvasively using plethysmography rest, after breathing supplemental oxygen, exercise. had more than double forearm low-altitude residents, resulting in greater to tissues. In comparison controls, >10-fold-higher circulating concentrations NO products, including plasma red cell nitrate nitroso proteins nitrite, but iron nitrosyl complexes (HbFeIINO) cells. suggests production is increased metabolic pathways controlling formation products regulated differently Tibetans. These findings shift attention from traditional focus on hematological systems factors contributing adaptation high-altitude hypoxia.