High-altitude physiology: lessons from Tibet

Peter D. Wagner; Tatum S. Simonson; Guan Wei; Harrieth Wagner; Tanna Wuren; Ma Yan; Ga Qin; Rili Ge

doi:10.1117/12.2020038

29 May 2013 High-altitude physiology: lessons from Tibet

Peter D. Wagner, Tatum S. Simonson, Guan Wei, Harrieth Wagner, Tanna Wuren, Ma Yan, Ga Qin, Rili Ge

Proceedings Volume 8723, Sensing Technologies for Global Health, Military Medicine, and Environmental Monitoring III; 87230S (2013) https://doi.org/10.1117/12.2020038
Event: SPIE Defense, Security, and Sensing, 2013, Baltimore, Maryland, United States

Abstract

Polycythemia is a universal lowlander response to altitude; healthy Andean high-altitude natives also have elevated [Hb]. While this may enhance O₂ transport to tissues, studies have shown that acute isovolumic changes in [Hb] do not affect exercise capacity. Many high-altitude Tibetans have evolved sea-level values of [Hb], providing a natural opportunity to study this issue. In 21 young healthy male Tibetans with [Hb] between 15 and 23 g/dl, we measured VO₂MAX and O₂ transport capacity at 4200m. VO₂MAX was higher when [Hb] was lower (P<0.05), enabled by both higher cardiac output and muscle O₂ diffusional conductance, but neither ventilation nor the alveolar-arterial PO₂ difference (AaPO₂) varied with [Hb]. In contrast, Andean high altitude natives remain polycythemic with larger lungs and higher lung diffusing capacity, a smaller exercising AaPO₂, and lower ventilation. The challenges now are (1) to understand the different adaptive pathways used by Andeans and Tibetans, and (2) to determine in Tibetans whether, during evolution, reduced [Hb] appeared first, causing compensatory cardiac and muscle adaptations, or if enhanced cardiac function and muscle O₂ transport capacity appeared first, permitting secondary reduction in [Hb]. For (2), further research is necessary to determine the basis of enhanced cardiac function and muscle O₂ transport, and identify molecular targets of evolution in heart and muscle. Putative mutations can then be timed and compared to appearance of those affecting [Hb].

Citation Download Citation

Peter D. Wagner, Tatum S. Simonson, Guan Wei, Harrieth Wagner, Tanna Wuren, Ma Yan, Ga Qin, and Rili Ge "High-altitude physiology: lessons from Tibet", Proc. SPIE 8723, Sensing Technologies for Global Health, Military Medicine, and Environmental Monitoring III, 87230S (29 May 2013); https://doi.org/10.1117/12.2020038

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