Institute for Biomedical Problems, Russian Academy of Sciences.
Acta Naturae. 2010 Jul;2(2):59-66.
Adult skeletal muscle fiber is a symplast multinuclear structure developed in ontogenesis by the fusion of the myoblasts (muscle progenitor cells). The nuclei of a muscle fiber (myonuclei) are those located at the periphery of fiber in the space between myofibrils and sarcolemma. In theory, a mass change in skeletal muscle during exercise or unloading may be associated with the altered myonuclear number, ratio of the transcription, and translation and proteolysis rates. Here we review the literature data related to the phenomenology and hypothetical mechanisms of the myonuclear number alterations during enhanced or reduced muscle contractile activity. In many cases (during severe muscle and systemic diseases and gravitational unloading), muscle atrophy is accompanied by a reduction in the amount of myonuclei. Such reduction is usually explained by the development of myonuclear apoptosis. A myonuclear number increase may be provided only by the satellite cell nuclei incorporation via cell fusion with the adjacent myofiber. It is believed that it is these cells which supply fiber with additional nuclei, providing postnatal growth, work hypertrophy, and repair processes. Here we discuss the possible mechanisms controlling satellite cell proliferation during exercise, functional unloading, and passive stretch.
成人骨骼肌纤维是一种由成肌细胞（肌肉祖细胞）融合而成的合胞体多核结构，在个体发生过程中发育。肌纤维的核（肌核）位于纤维的外周，位于肌原纤维和肌膜之间的空间内。理论上，运动或去负荷期间骨骼肌质量的变化可能与肌核数量的改变、转录和翻译以及蛋白水解率的比值有关。在这里，我们回顾了与增强或减少肌肉收缩活动期间肌核数量改变的现象学和假设机制相关的文献数据。在许多情况下（在严重的肌肉和全身疾病以及重力去负荷期间），肌肉萎缩伴随着肌核数量的减少。这种减少通常是通过肌核凋亡的发展来解释的。肌核数量的增加只能通过卫星细胞核与相邻肌纤维融合的细胞融合来提供。人们认为正是这些细胞为纤维提供了额外的核，为出生后的生长、工作肥大和修复过程提供了支持。在这里，我们讨论了控制运动、功能去负荷和被动拉伸过程中卫星细胞增殖的可能机制。
