THE CONTRIBUTION OF MUSCLE PROGENITOR CELLS TO MAINTAINING MORPHOLOGICAL CHARACTERISTICS OF UNWEIGHTED RAT SOLEUS
MUSCLE DURING PASSIVE STRETCH
M. V. Tarakina,1 O. V. Turtikova,1 T. L. Nemirovskaya,1 A. A. Kokontcev,2
B. S. Shenkman 1, *
1 Institute for Biomedical Problems RAS and 2 Institute of Medical Radiology, Moscow;
* e-mail: shenkman@imbp.ru
Skeletal muscle work hypertrophy is usually connected with muscle progenitor SC (satellite cells) activation with subsequent incorporation their nuclei into
myofibers. Passive stretch of unloaded muscle was earlier established to prevent atrophic processes and be accompanied by enhanced protein synthesis. We
hypothesized that elimination of SC proliferation capacity by γ-irradiation would partly preavent stretched muscle fiber capability to maintain their size under
condition of gravitational unloading. To assess the role of muscle progenitor (satellite) cells in development of passive stretch preventive effect SC proliferation was
suppressed by local exposure to ionizing radiation (2500 Rad) and then subsequent hindlimb suspension or hindlimb suspension with concomitant passive stretch
were carried out. Reduction of myofiber cross-sectional area and decrease in myonuclei number accompanying unloaded muscle atrophy were completely abolished
by passive stretch both in irradiated and sham-treated animals. We concluded that satellite cells did not make essential contribution to passive stretch preventive
action under condition of simulated weightlessness.
Key words: gravitational unloading, miofibers, immunohistochemistry, m. soleus, passive stretch, myonuclei, satellite cells
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