Prolonged space flight-induced alterations in the structure and function of human skeletal muscle fibres
Prolonged space flight-induced alterations in the structure and function of human skeletal muscle fibres
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DOI：
10.1113/jphysiol.2010.188508
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发表时间：
2010-09-15
影响因子：
5.5
通讯作者：
Riley, D. A.
中科院分区：
文献类型：
--
作者：
Fitts, R. H.;Trappe, S. W.;Riley, D. A.
这项研究的主要目的是确定长时间空间飞行（类似于180天）对人体骨骼肌中慢纤维和快纤维的结构和功能的影响。从9名国际空间站机组人员的腓肠肌和比目鱼肌中获取了类似于飞行前45天和着陆日（R+0）飞行后的活组织检查。主要的研究结果是，长时间的失重会造成纤维质量、力量和动力的大量损失，其影响的层次是比目鱼肌I型>比目鱼肌II型>腓肠肌I型>腓肠肌II型。从结构上看，数量上最重要的适应是纤维萎缩，比目鱼肌I型纤维（直径98至79 μ m）平均萎缩20%。萎缩是导致峰值力（P（0））损失的主要因素，比目鱼肌I型纤维的峰值力从0.86 mN下降到0.56 mN，下降了35%。纤维直径的百分比下降与初始飞行前纤维尺寸相关（r = 0.87），与跑步机跑步量成反比（r = 0.68），并且与细丝密度的增加相关（r = 0.92）。后者与最大速度（V（0））降低相关（r = -0.51），可能导致比目鱼肌和腓肠肌I型纤维V（0）下降21%和18%。峰值功率在所有类型的纤维与最大的损失（类似于55%）在比目鱼肌被压抑。一个明显的结论是，所采用的运动对策无法提供足够保护纤维和肌肉质量所需的高强度，船员进行剧烈运动的能力可能会受到严重影响。我们的研究结果强调了在国际空间站上研究新的运动方案的必要性，这些方案在广泛的运动范围内采用高阻力和收缩，以模仿地球1 g环境中发生的范围。
The primary goal of this study was to determine the effects of prolonged space flight (similar to 180 days) on the structure and function of slow and fast fibres in human skeletal muscle. Biopsies were obtained from the gastrocnemius and soleus muscles of nine International Space Station crew members similar to 45 days pre- and on landing day (R+0) post-flight. The main findings were that prolonged weightlessness produced substantial loss of fibre mass, force and power with the hierarchy of the effects being soleus type I > soleus type II > gastrocnemius type I > gastrocnemius type II. Structurally, the quantitatively most important adaptation was fibre atrophy, which averaged 20% in the soleus type I fibres (98 to 79 mu m diameter). Atrophy was the main contributor to the loss of peak force (P(0)), which for the soleus type I fibre declined 35% from 0.86 to 0.56 mN. The percentage decrease in fibre diameter was correlated with the initial pre-flight fibre size (r = 0.87), inversely with the amount of treadmill running (r = 0.68), and was associated with an increase in thin filament density (r = 0.92). The latter correlated with reduced maximal velocity (V(0)) (r = -0.51), and is likely to have contributed to the 21 and 18% decline in V(0) in the soleus and gastrocnemius type I fibres. Peak power was depressed in all fibre types with the greatest loss (similar to 55%) in the soleus. An obvious conclusion is that the exercise countermeasures employed were incapable of providing the high intensity needed to adequately protect fibre and muscle mass, and that the crew's ability to perform strenuous exercise might be seriously compromised. Our results highlight the need to study new exercise programmes on the ISS that employ high resistance and contractions over a wide range of motion to mimic the range occurring in Earth's 1 g environment.