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Skeletal muscle immobilized in a stretched position does not display characteristics of disuse atrophy (1163.1)
Author(s) -
Kelleher Andrew,
Gordon Bradley,
Luongo Lauren,
Kimball Scot,
Jefferson Leonard
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1163.1
Subject(s) - skeletal muscle , atrophy , soleus muscle , muscle atrophy , mtorc1 , phosphorylation , chemistry , hindlimb , medicine , anatomy , endocrinology , sarcopenia , biology , biochemistry , protein kinase b
In a recent report we showed that skeletal muscle immobilized in a shortened position exhibits atrophy in association with reduced rates of protein synthesis and mTORC1 signaling. The objective of the present study was to test the hypothesis that, in contrast to the effects of immobilizing skeletal muscle in a shortened position, muscle immobilized in a stretched position would be resistant to the development of disuse atrophy. To test the hypothesis, male Sprague‐Dawley rats were subjected to unilateral hindlimb immobilization for 3 days with the soleus muscle placed in either a shortened or stretched position. All comparisons were made to the contralateral non‐immobilized muscle. Soleus muscles immobilized in a shortened position exhibited disuse atrophy, attenuated rates of protein synthesis, attenuated phosphorylation of Thr389 on the mTORC1 substrate p70S6K1, and induction of the mTORC1 repressors REDD1 and REDD2. Muscles immobilized in a stretched position exhibited no difference in muscle mass, rates of protein synthesis, p70S6K1 phosphorylation, or REDD1 expression and a slight reduction in REDD2 expression. In conclusion, fixed muscle length plays a major role in immobilization‐induced skeletal muscle atrophy whereby muscle placed in a stretched position exhibits resistance to disuse atrophy. Grant Funding Source : Supported by NIH Grant DK‐15658