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Synergistic ablation does not affect atrophy or altered myosin heavy chain expression in the non-weight bearing soleus muscleThe purpose of this study was to investigate whether the soleus muscle undergoes atrophy and alterations in myosin heavy chain (MHC) composition during non-weight bearing in the absence of synergists. Thirty-two female rats were randomly assigned to four groups: control (C), synergistic ablation (ABL) of the gastrocnemius and plantaris muscles to overload the soleus muscle, hindlimb suspension (HLS), or a combination of synergistic ablation and hindlimb suspension (HLS-ABL). After 28 days of hindlimb suspension, soleus atrophy was more pronounced in HLS (58%) than in HLS-ABL (43%) rats. Compared to C rats, non-weight bearing decreased mixed and myofibrillar protein contents and Type I MHC 49%, 45%, and 7%, respectively, in HLS animals. In addition, de novo expression of fast Type IIx and Type IIb MHC (5% and 2%, respectively) was observed in HLS animals. Similarly, when compared to C rats, mixed and myofibrillar protein contents and Type I MHC decreased 43%, 46%, and 4%, respectively, in HLS-ABL animals. Also, de novo expression of Type IIx (4%) and IIb (1%) MHC was observed. Collectively, these data indicate that the loss of muscle protein and Type I MHC, and the de novo expression of Type IIx and Type IIb MHC in the rat soleus occur independently of the presence of synergists during non-weight bearing. Furthermore, these results confirm the contention that soleus mass and MHC expression are highly sensitive to alterations in mechanical load.
Document ID
20040173309
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Linderman, J. K.
(NASA Ames Research Center Moffett Field, CA United States)
Talmadge, R. J.
Gosselink, K. L.
Tri, P. N.
Roy, R. R.
Grindeland, R. E.
Date Acquired
August 22, 2013
Publication Date
January 1, 1996
Publication Information
Publication: Life sciences
Volume: 59
Issue: 10
ISSN: 0024-3205
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: DE07212
Distribution Limits
Public
Copyright
Other
Keywords
NASA Center ARC
NASA Discipline Musculoskeletal
NASA Discipline Number 26-10
NASA Program Space Physiology and Countermeasures

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