Favier R, Desplanches D, Hoppeler H, Caceres E, Grunenfelder A, Koubi H, Leuenberger M, Sempore B, Tuscher L, Spielvogel H
Instituto Boliviano de Biologia de Altura, La Paz, Bolivia.
J Appl Physiol (1985). 1996 Feb;80(2):632-7. doi: 10.1152/jappl.1996.80.2.632.
In sea-level natives, exposure to hypoxia for a few weeks is characterized by an increased dependence on blood glucose and a decreased reliance on lactate for energy metabolism during exercise. These metabolic adjustments have been attributed to behavioral changes in the sympathoadrenergic and pancreatic systems. The aim of this study was to test the hypothesis of a reduced sympathoadrenergic activation and subsequent metabolic changes when high-altitude natives are acutely exposed to normoxia. Young Andean natives performed incremental exercise to exhaustion during hypoxia (arterial PO2 55.1 +/- 1.1 Torr) or during acute normoxia (arterial PO2 78.7 +/- 1.7 Torr). As a whole, oxygen uptake was increased in normoxia compared with hypoxia during graded exercise. This finding is not related to a decrease in anaerobic metabolism but rather is interpreted as a consequence of a shift in substrate utilization during exercise (increased contribution of fat as assessed by a reduction in the respiratory exchange ratio). These metabolic changes are not accompanied by modifications of glucoregulatory hormones (catecholamines, insulin, and glucagon). In particular, the exercise-induced catecholamine secretion was similar in chronic hypoxia and acute normoxia. As a consequence, blood lactate accumulation during incremental exercise was similar in both conditions. It is concluded that high-altitude natives do not display any sign of a greater sympathoadrenergic activation during chronic hypoxia and that the exercise-induced hormonal changes remained unaffected by acute inhalation of a normoxic gas mixture.
在海平面地区的本地人中，暴露于低氧环境几周的特征是在运动期间对血糖的依赖性增加，而对乳酸作为能量代谢底物的依赖性降低。这些代谢调整归因于交感肾上腺素能和胰腺系统的行为变化。本研究的目的是检验高海拔地区本地人急性暴露于常氧环境时交感肾上腺素能激活减弱及随后代谢变化这一假说。年轻的安第斯本地人在低氧（动脉血氧分压55.1±1.1托）或急性常氧（动脉血氧分压78.7±1.7托）状态下进行递增运动直至力竭。总体而言，在分级运动期间，与低氧相比，常氧状态下的摄氧量增加。这一发现与无氧代谢的减少无关，而是被解释为运动期间底物利用发生转变的结果（通过呼吸交换率降低评估，脂肪的贡献增加）。这些代谢变化并未伴随糖调节激素（儿茶酚胺、胰岛素和胰高血糖素）的改变。特别是，运动诱导的儿茶酚胺分泌在慢性低氧和急性常氧状态下相似。因此，在两种情况下递增运动期间的血乳酸积累相似。得出的结论是，高海拔地区本地人在慢性低氧期间未表现出交感肾上腺素能激活增强的任何迹象，并且运动诱导的激素变化不受急性吸入常氧气体混合物的影响。
