Curran L S, Zhuang J, Sun S F, Moore L G
Department of Anthropology, University of Colorado at Denver, Denver 80217-3364, USA.
J Appl Physiol (1985). 1997 Dec;83(6):2098-104. doi: 10.1152/jappl.1997.83.6.2098.
When breathing ambient air at rest at 3,658 m altitude, Tibetan lifelong residents of 3,658 m ventilate as much as newcomers acclimatized to high altitude; they also ventilate more and have greater hypoxic ventilatory responses (HVRs) than do Han ("Chinese") long-term residents at 3,658 m. This suggests that Tibetan ancestry is advantageous in protecting resting ventilation levels during years of hypoxic exposure and is of interest in light of the permissive role of hypoventilation in the development of chronic mountain sickness, which is nearly absent among Tibetans. The existence of individuals with mixed Tibetan-Chinese ancestry (Han-Tibetans) residing at 3,658 m affords an opportunity to test this hypothesis. Eighteen men born in Lhasa, Tibet, China (3,658 m) to Tibetan mothers and Han fathers were compared with 27 Tibetan men and 30 Han men residing at 3,658 m who were previously studied. We used the same study procedures (minute ventilation was measured with a dry-gas flowmeter during room air breathing and hyperoxia and with a 13-liter spirometer-rebreathing system during the hypoxic and hypercapnic tests). During room air breathing at 3,658 m (inspired O2 pressure = 93 Torr), Han-Tibetans resembled Tibetans in ventilation (12.1 +/- 0.6 vs. 11.5+/- 0.5 l/min BTPS, respectively) but had HVR that were blunted (63 +/- 16 vs. 121 +/- 13, respectively, for HVR shape parameter A) and declined with increasing duration of high-altitude residence. During administered hyperoxia (inspired O2 pressure = 310 Torr) at 3,658 m, the paradoxical hyperventilation previously seen in Tibetan but not Han residents at 3,658 m (11.8 +/- 0.5 vs. 10.1 +/- 0.5 l/min BTPS) was absent in these Han-Tibetans (9.8 +/- 0.6 l/min BTPS). Thus, although longer duration of high-altitude residence appears to progressively blunt HVR among Han-Tibetans born and residing at 3, 658 m, their Tibetan ancestry appears protective in their maintenance of high resting ventilation levels despite diminished chemosensitivity.
在海拔3658米处静息呼吸环境空气时，出生并终生居住在海拔3658米的藏族人与适应了高海拔环境的新来者通气量相当；与长期居住在海拔3658米的汉族（“中国人”）相比，他们的通气量更大，且具有更强的低氧通气反应（HVRs）。这表明藏族血统有利于在多年低氧暴露期间保护静息通气水平，鉴于通气不足在慢性高山病发生中的作用，这一点很有意思，而慢性高山病在藏族中几乎不存在。居住在海拔3658米的具有藏汉混合血统（汉藏混血）的个体的存在为检验这一假设提供了机会。将18名出生在中国西藏拉萨（海拔3658米）、母亲为藏族、父亲为汉族的男性与27名居住在海拔3658米的藏族男性和30名居住在海拔3658米的汉族男性进行比较，后者曾参与过研究。我们采用相同的研究程序（在呼吸室内空气和高氧时用干式气体流量计测量分钟通气量，在低氧和高碳酸血症试验时用13升肺量计-再呼吸系统测量）。在海拔3658米呼吸室内空气时（吸入氧分压=93托），汉藏混血儿的通气量与藏族人相似（分别为12.1±0.6和11.5±0.5升/分钟BTPS），但其HVR减弱（HVR形状参数A分别为63±16和121±13），并随着在高海拔居住时间的增加而下降。在海拔3658米进行高氧吸入时（吸入氧分压=310托），这些汉藏混血儿没有出现之前在海拔3658米的藏族居民中出现而汉族居民中未出现的矛盾性过度通气（分别为11.8±0.5和10.1±0.5升/分钟BTPS）（为9.8±0.6升/分钟BTPS）。因此，尽管在海拔3658米出生并居住的汉藏混血儿中，较长的高海拔居住时间似乎会逐渐减弱其HVR，但他们的藏族血统似乎在维持高静息通气水平方面具有保护作用，尽管化学敏感性有所降低。
