Human Adaptation to the Tibetan Plateau

摘要

Humans have lived at high altitude for longer periods of time on the TibetanPlateau than elsewhere in the world, thus providing opportunity to investigate the physiologic effects of long-term (years to generation) duration of high altitude exposure. This has military importance because persons are stationed at high altitudes for extended periods of time and experience marked decrements in performance and health. Knowledge as to the physiologic traits required for successful high-altitude adjustment is important for the selection of personnel resistant to the ill effects of high altitude and for the treatment of afflicted individuals. The results of this research supported the underlying hypothesis that Tibetans are better-adapted to high altitude than acclimatized newcomers in Tibet or than persons elsewhere in the world as judged from literature reports. The Tibetans' superiority was evidenced by: greater maximal oxygen uptake, higher work capacity, increased greater vital capacity and lung volume, decreased alveolar-arterial oxygen diffusion gradient, absence of hypoxic pulmonary vasoconstriction, increased cardiac output and increased tissue oxygen utilization. In addition, Tibetans are resistant to the development of Chronic Mountain Sickness. Compared to healthy controls, persons with Chronic Mountain Sickness breathe less and have lower arterial oxygen saturations than healthy persons, due to the absence of hypoxic ventilatory sensitivity and greater hypoxic ventilatory depression, and likely suffer from decrements in nocturnal brain oxygen delivery.