Oganov V S, Potapov A N
Institute for Medico-Biological Problems, Academy of Sciences of the USSR, Moscow, USSR.
Life Sci Space Res. 1976;14:137-43.
Some characteristics of muscle contraction and mechanical properties of two muscles (M. soleus and M. extensor digitorum longus) in Wistar rats after 22 days of weightlessness have been investigated. On the second day after return to earth, the following changes were evident: slowing of twitch responses of the muscles studied; shortening half tetanic contraction time (defined by point of interactions of the increasing curve with 50% level of the peak value) in soleus; a rise of tension in both muscles as shown by the curve "length-force"; an increase of twitch/tetanus ratio and fatigability in both muscles. During repeated study of muscle properties, on the 26th day after return to earth, there were not any significant changes in values of most the above mentioned indices except the diminished strength of soleus. Shortening of contraction time in slow antigravitary soleus muscle is believed to be a sign of adaptive change in its characteristics resulting from unloading under the conditioning of weightlessness. Increased stiffness and diminished strength of muscles are considered as functional signs of atrophic processes, developing in the experiment. Dynamics of functional changes, conditioned, as we believe, mainly by weightlessness and correlated with morphological and biochemical data obtained on analogous material, allows us to postulate a reversible character of the changes described.
研究了失重22天后Wistar大鼠两块肌肉（比目鱼肌和趾长伸肌）的肌肉收缩特征和力学特性。返回地球后的第二天，明显出现了以下变化：所研究肌肉的抽搐反应减慢；比目鱼肌的半强直收缩时间缩短（由增长曲线与峰值50%水平的交点定义）；两条肌肉的张力如“长度-力”曲线所示升高；两条肌肉的抽搐/强直比值和疲劳性增加。在返回地球后的第26天对肌肉特性进行重复研究时，除比目鱼肌力量减弱外，上述大多数指标的值没有任何显著变化。慢抗重力比目鱼肌收缩时间的缩短被认为是在失重条件下卸载导致其特性发生适应性变化的一个标志。肌肉刚度增加和力量减弱被视为实验中正在发生的萎缩过程的功能标志。我们认为，主要由失重引起的功能变化动态，并与在类似材料上获得的形态学和生化数据相关，使我们能够假设所描述变化的可逆性。
