Jacobs Robert A, Lundby Anne-Kristine Meinild, Fenk Simone, Gehrig Saskia, Siebenmann Christoph, Flück Daniela, Kirk Niels, Hilty Matthias P, Lundby Carsten
Zürich Centre for Integrative Human Physiology, Institute of Physiology, University of Zürich, Switzerland.
Health and Physical Education, School of Teaching and Learning, Western Carolina University, Cullowhee, NC, USA.
J Physiol. 2016 Mar 1;594(5):1151-66. doi: 10.1113/JP271118. Epub 2015 Oct 28.
The role of hypoxia on skeletal muscle mitochondria is controversial. Studies superimposing exercise training on hypoxic exposure demonstrate an increase in skeletal muscle mitochondrial volume density (Mito(VD)) over equivalent normoxic training. In contrast, reductions in both skeletal muscle mass and Mito(VD) have been reported following mountaineering expeditions. These observations may, however, be confounded by negative energy balance, which may obscure the results. Accordingly we sought to examine the effects of high altitude hypoxic exposure on mitochondrial characteristics, with emphasis on Mito(VD), while minimizing changes in energy balance. For this purpose, skeletal muscle biopsies were obtained from nine lowlanders at sea level (Pre) and following 7 and 28 days of exposure to 3454 m. Maximal ergometer power output, whole body weight and composition, leg lean mass and skeletal muscle fibre area all remained unchanged following the altitude exposure. Transmission electron microscopy determined that intermyofibrillar (IMF) Mito(VD) was augmented (P = 0.028) by 11.5 ± 9.2% from Pre (5.05 ± 0.9%) to 28 Days (5.61 ± 0.04%). In contrast, there was no change in subsarcolemmal (SS) Mito(VD). As a result, total Mito(VD) (IMF + SS) was increased (P = 0.031) from 6.20 ± 1.5% at Pre to 6.62 ± 1.4% at 28 Days (7.8 ± 9.3%). At the same time no changes in mass-specific respiratory capacities, mitochondrial protein or antioxidant content were found. This study demonstrates that skeletal muscle Mito(VD) may increase with 28 days acclimation to 3454 m.
缺氧对骨骼肌线粒体的作用存在争议。将运动训练与低氧暴露相结合的研究表明，与同等常氧训练相比，骨骼肌线粒体体积密度（Mito(VD)）有所增加。相比之下，有报道称登山探险后骨骼肌质量和Mito(VD)均有所下降。然而，这些观察结果可能会因负能量平衡而混淆，负能量平衡可能会掩盖结果。因此，我们试图研究高海拔低氧暴露对线粒体特征的影响，重点是Mito(VD)，同时尽量减少能量平衡的变化。为此，从9名海平面的低地居民身上获取骨骼肌活检样本，分别在海拔3454米暴露7天和28天后再次取样。海拔暴露后，最大测力计功率输出、全身重量和组成、腿部瘦体重和骨骼肌纤维面积均保持不变。透射电子显微镜测定显示，肌原纤维间（IMF）的Mito(VD)从暴露前（5.05±0.9%）到28天（5.61±0.04%）增加了11.5±9.2%（P = 0.028）。相比之下，肌膜下（SS）的Mito(VD)没有变化。因此，总Mito(VD)（IMF + SS）从暴露前的6.20±1.5%增加到28天的6.62±1.4%（7.8±9.3%）（P = 0.031）。同时，未发现质量特异性呼吸能力、线粒体蛋白或抗氧化剂含量有变化。这项研究表明，骨骼肌Mito(VD)可能会随着28天适应3454米海拔高度而增加。
