Skeletal muscle protein synthesis after active or passive ascent to high altitude
Skeletal muscle protein synthesis after active or passive ascent to high altitude
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DOI：
10.1249/01.mss.0000222836.66391.35
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发表时间：
2006-06-01
期刊：
影响因子：
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通讯作者：
Ballmer, Peter E.
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文献类型：
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作者：
Imoberdorf, Reinhard;Garlick, Peter J.;Ballmer, Peter E.
简介：研究了急性高原暴露对人体肌肉蛋白质合成速率的影响。方法：在低海拔（550 m）进行首次测量，并在上升到高海拔（4559 m）后再次测量。为了能够区分体育锻炼的贡献，一组乘坐直升机（空中组，N = 8），而另一组爬到高海拔（脚组，N = 9）。肌肉蛋白质合成率（FSR）的分数率由注射[（2）H（5）环]苯丙氨酸后同位素掺入蛋白质测定。结果如下：在空气组中，没有变化;在高海拔的FSR，而在足组中，在攀登结束后19-23小时测量的FSR增加了35%（P < 0.05）。在高原，各组间的缺氧和水肿程度无差异。胰岛素样生长因子-1、游离甲状腺素、游离三碘甲状腺原氨酸和促甲状腺激素的血浆浓度在两组之间没有差异。上升后两组24小时尿皮质醇排泄量均显著增加，但足组的增加量显著高于空气组。结论：体育锻炼似乎是肌肉FSR增加的原因。足组24小时皮质醇排泄量的显著增加表明，尽管糖皮质激素水平较高，但FSR增加，糖皮质激素通常通过抑制蛋白质合成影响肌肉蛋白质周转。
Introduction: The effects of acute exposure to high altitude on muscle protein synthesis rates in human volunteers were examined after active and passive ascent. Methods: Measurements were made initially at low altitude (550 m) and again after ascent to high altitude (4559 m). To be able to separate the contribution of physical exercise, one group was flown by helicopter (air group, N = 8), whereas the other group climbed to high altitude (foot group, N = 9). Fractional rates of muscle protein synthesis rates (FSR) were determined from the incorporation of isotope into protein after injection of [(2)H(5)ring] phenylalanine. Results: In the air group, there was no change; in FSR at high altitude, whereas in the foot group, there was a 35% increase in FSR (P < 0.05 for interaction) measured 19-23 h after the end of climbing. At high altitude, the degree of hypoxia and alkalosis were not different between the groups. The plasma concentration of insulin-like growth factor-1, free thyroxin, free triiodothyronine, and thyroid-stimulating hormone were not different between the groups. Urinary 24-h cortisol excretion increased significantly in both groups after ascent, but the increase in the foot group was significantly higher compared with the air group. Conclusion: Physical exercise appeared to be responsible for the observed increase in muscle FSR. The significantly higher increase of 24-h cortisol excretion in the foot group suggests that the increase in FSR occurred despite higher levels of glucocorticoids, which generally affect muscle protein turnover by inhibiting protein synthesis.