Kischel P, Stevens L, Montel V, Picquet F, Mounier Y
Laboratoire de Plasticité Neuromusculaire, Université des Sciences et Technologies de Lille 1, F-59655 Villeneuve d'Ascq Cedex, France.
J Appl Physiol (1985). 2001 May;90(5):1825-32. doi: 10.1152/jappl.2001.90.5.1825.
We examined the changes in functional properties of triceps brachii skinned fibers from monkeys flown aboard the BION 11 satellite for 14 days and after ground-based arm immobilization. The composition of myosin heavy chain (MHC) isoforms allowed the identification of pure fibers containing type I (slow) or type IIa (fast) MHC isoforms or hybrid fibers coexpressing predominantly slow (hybrid slow; HS) or fast (hybrid fast) MHC isoforms. The ratio of HS fibers to the whole slow population was higher after flight (28%) than in the control population (7%), and the number of fast fibers was increased (up to 86% in flight vs. 12% in control). Diameters and maximal tensions of slow fibers were decreased after flight. The tension-pCa curves of slow and fast fibers were modified, with a decrease in pCa threshold and an increase in steepness. The proper effect of microgravity was distinguishable from that of immobilization, which induced less marked slow-to-fast transitions (only 59% of fast fibers) and changed the tension-pCa relationships.
我们研究了搭乘“生物11号”卫星飞行14天的猴子以及地面手臂固定后的猴子肱三头肌脱细胞纤维功能特性的变化。肌球蛋白重链（MHC）同工型的组成使得能够鉴定出含有I型（慢肌）或IIa型（快肌）MHC同工型的纯纤维，或主要共表达慢肌（混合慢肌；HS）或快肌（混合快肌）MHC同工型的混合纤维。飞行后，HS纤维与整个慢肌群体的比例（28%）高于对照组（7%），快肌纤维数量增加（飞行组高达86%，对照组为12%）。飞行后慢肌纤维的直径和最大张力降低。慢肌和快肌纤维的张力-pCa曲线发生改变，pCa阈值降低，斜率增加。微重力的适当作用与固定的作用可区分开来，固定引起的慢肌向快肌的转变不太明显（只有59%的快肌纤维），并改变了张力-pCa关系。
