Limited muscle oxygen diffusive transport during exercise in humans
Limited muscle oxygen diffusive transport during exercise in humans
复制标题
人体运动过程中肌肉氧扩散运输有限
DOI：
10.1117/12.2550671
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
T. Hamaoka.
中科院分区：
文献类型：
--
作者：
Kime;R.;T. Endo;R. Tanaka;S. Fuse;M. Kuroiwa;Y. Kurosawa;T. Hamaoka.
线粒体氧化磷酸化调节PCr的再合成，部分取决于工作肌肉中线粒体的O2可用性。特别是在剧烈运动期间，由于血流不足引起的缺氧条件导致的低O2可用性影响线粒体氧化磷酸化。然而，很少有研究报道了在不同负荷运动期间，包括在人类严重酸中毒条件下，线粒体刺激与骨骼肌中从毛细血管到线粒体的氧扩散速率（肌肉rDO 2）之间的关系。本研究的目的是调查肌肉PCr，rDO 2，和肌肉脱氧在人体递增动态运动过程中的关系。12名健康、不吸烟的男性受试者参加了本研究。受试者进行递增式动态握力练习，直至力竭。运动过程中的肌肉PCr使用31-磷磁共振波谱进行评估。使用近红外光谱监测肌肉脱氧水平，并在每个运动阶段结束后立即通过暂时动脉闭塞期间的肌肉脱氧速率来确定肌肉rDO 2。肌肉PCr水平随负荷增加而降低，rDO 2在10%MVC以上显著高于静息状态，但随负荷增加而保持恒定。肌肉脱氧水平也明显高于10%MVC，并随着工作负荷的增加而逐渐增加。这些结果表明，肌肉rDO 2是有限的，在较高的工作负荷，虽然线粒体刺激增加。高负荷时肌肉rDO 2恒定可能是由于毛细血管向线粒体的氧梯度降低所致。
Mitochondrial oxidative phosphorylation, which modulates resynthesis of PCr, depends in part on the availability of O2for the mitochondria in working muscle. Particularly during intense exercise, the induced lower O2availability due to hypoxic condition by inadequate blood flow affects mitochondrial oxidative phosphorylation. However, there are few studies which have reported the relationship between mitochondrial stimuli and oxygen diffusion rate from capillary to mitochondria in skeletal muscle (muscle rDO2) during varying-workload exercise including under severe acidosis conditions in humans. The purpose of this study was to investigate the relationship between muscle PCr, rDO2, and muscle deoxygenation in humans during incremental dynamic exercise. Twelve healthy, nonsmoking male subjects participated in this study. The subjects performed incremental dynamic handgrip exercise until exhaustion. Muscle PCr during exercise was evaluated using 31-phosphorus magnetic resonance spectroscopy. Muscle deoxygenation level was monitored using near-infrared spectroscopy, and muscle rDO2was determined by the rate of muscle deoxygenation during temporary arterial occlusion immediately after the end of each exercise stage. Muscle PCr level subsequently decreased with higher workloads, and muscle rDO2above 10%MVC significantly increased from the resting, and was constant with higher workloads. Muscle deoxygenation level was also significantly greater above 10%MVC, and gradually increased with higher workloads. These results suggest that muscle rDO2is limited at higher workloads, although mitochondrial stimuli are increased. The constant muscle rDO2with higher workloads may be caused by reduced O2gradient from capillary to mitochondria.