Decreased thin filament density and length in human atrophic soleus muscle fibers after spaceflight
Decreased thin filament density and length in human atrophic soleus muscle fibers after spaceflight
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DOI：
10.1152/jappl.2000.88.2.567
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发表时间：
2000-02-01
影响因子：
3.3
通讯作者：
Costill, DL
中科院分区：
文献类型：
--
作者：
Riley, DA;Bain, JLW;Costill, DL
在生命和微重力科学空间实验室使命（1996年6月）期间，对在轨道上飞行了17天的4名宇航员的飞行前和飞行后活组织检查进行了比目鱼肌纤维电子显微镜检查。肌丝密度和间距归一化为2.4 μ m肌节长度。太空飞行后，粗丝密度（类似于1，062根丝/μ m（2））和间距（类似于32.5纳米）没有变化。由于17%的细丝损失和9%的短丝增加，在重叠A带区域，飞行前细丝密度（2，976/μ m（2））显著降低（P < 0.01）至2，215/μ m（2）。正常纤维有13%的短细丝。细肌丝减少26%与肌球蛋白-肌动蛋白比率增加14%的初步结果一致。计算较低的细丝密度以将体内粗细丝间距从17 nm增加到23 nm。假设密度降低促进更早的跨桥脱离和更快的收缩速度。萎缩性纤维可能更容易受到肌节重新加载损伤，因为每细丝的力估计增加23%。
Soleus muscle fibers were examined electron microscopically from pre- and postflight biopsies of four astronauts orbited for 17 days during the Life and Microgravity Sciences Spacelab Mission (June 1996). Myofilament density and spacing were normalized to a 2.4-mu m sarcomere length. Thick filament density (similar to 1,062 filaments/mu m(2)) and spacing (similar to 32.5 nm) were unchanged by spaceflight. Preflight thin filament density (2,976/mu m(2)) decreased significantly (P < 0.01) to 2,215/mu m(2) in the overlap A band region as a result of a 17% filament loss and a 9% increase in short filaments. Normal fibers had 13% short thin filaments. The 26% decrease in thin filaments is consistent with preliminary findings of a 14% increase in the myosin-to-actin ratio. Lower thin filament density was calculated to increase thick-to-thin filament spacing in vivo from 17 to 23 nm. Decreased density is postulated to promote earlier cross-bridge detachment and faster contraction velocity. Atrophic fibers may be more susceptible to sarcomere reloading damage, because force per thin filament is estimated to increase by 23%.