Ilyin E A, Oganov V S
Institute of Biomedical Problems, USSR Ministry of Health, Moscow.
Adv Space Res. 1989;9(11):11-9. doi: 10.1016/0273-1177(89)90048-3.
This review surveys data in the literature and our own findings concerning the effects of weightlessness on bones and muscles of white rats flown on Cosmos biosatellites and Spacelab-3. It has been shown that the magnitude and sign of functional changes in muscles depend on their biomechanical profile. Structural and metabolic foundations of functional adaptation and its dynamics have been identified: in 5-7 day flights muscle contractility changes are mainly associated with a diminished activity of excitation-contraction coupling, in longer-term flights they are produced by changes in myosin populations specific for myofibers of different functional profile. At early flight stages (up to 1 week) osteoporosis and bone demineralization are very mild; therefore decrease in bone mechanical strength may be caused by changes in physico-chemical parameters of the collagen-crystal system. In flights of up to 3 weeks noticeable osteoporosis develops which is primarily produced by osteogenesis inhibition and which is responsible for a marked decrease of bone strength. These changes may result from uncoupling of bone resorption and remodelling processes. This uncoupling is characterized as incomplete osteogenesis and may be caused by changes in the collagen composition of the organic bone matrix. The above-mentioned adaptive changes in muscle functions of specific skeletal compartments may play a role in different responses of various bones to weightlessness.
本综述研究了文献数据以及我们自己关于失重对搭乘宇宙生物卫星和太空实验室-3飞行的白鼠骨骼和肌肉影响的研究结果。结果表明，肌肉功能变化的幅度和特征取决于其生物力学特征。已经确定了功能适应及其动态变化的结构和代谢基础：在5至7天的飞行中，肌肉收缩性变化主要与兴奋-收缩偶联活动减弱有关；在长期飞行中，它们是由不同功能特征的肌纤维中肌球蛋白群体的变化引起的。在飞行早期阶段（长达1周），骨质疏松和骨质脱矿非常轻微；因此，骨机械强度的降低可能是由胶原-晶体系统的物理化学参数变化引起的。在长达3周的飞行中，会出现明显的骨质疏松，这主要是由成骨抑制引起的，并导致骨强度显著降低。这些变化可能是由于骨吸收和重塑过程的解偶联所致。这种解偶联的特征是不完全成骨，可能是由有机骨基质胶原成分的变化引起的。特定骨骼部位肌肉功能的上述适应性变化可能在不同骨骼对失重的不同反应中起作用。
