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Myosin heavy chain expression in rodent skeletal muscle: effects of exposure to zero gravityThis study ascertained the effects of 9 days of zero gravity on the relative (percentage of total) and calculated absolute (mg/muscle) content of isomyosin expressed in both antigravity and locomotor skeletal muscle of ground control (CON) and flight-exposed (FL) rats. Results showed that although there were no differences in body weight between FL and CON animals, a significant reduction in muscle mass occurred in the vastus intermedius (VI) (P < 0.05) but not in the vastus lateralis (VL) or the tibialis anterior. Both total muscle protein and myofibril protein content were not different between the muscle regions examined in the FL and CON groups. In the VI, there were trends for reductions in the relative content of type I and IIa myosin heavy chains (MHCs) that were offset by increases in the relative content of both type IIb and possibly type IIx MHC protein (P > 0.05). mRNA levels were consistent with this pattern (P < 0.05). The same pattern held true for the red region of the VL as examined at both the protein and mRNA level (P < 0.05). When the atrophy process was examined, there were net reductions in the absolute content of both type I and IIa MHCs that were offset by calculated increases in type IIb MHC in both VI and red VL. Collectively, these findings suggest that there are both absolute and relative changes occurring in MHC expression in the "red" regions of antigravity skeletal muscle during exposure to zero gravity that could affect muscle function.
Document ID
20050000417
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Haddad, F.
(College of Medicine, University of California Irvine 92717)
Herrick, R. E.
Adams, G. R.
Baldwin, K. M.
Date Acquired
August 22, 2013
Publication Date
December 1, 1993
Publication Information
Publication: Journal of applied physiology (Bethesda, Md. : 1985)
Volume: 75
Issue: 6
ISSN: 8750-7587
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
short duration
NASA Program Flight
Non-NASA Center
NASA Experiment Number 178127 1/3
NASA Discipline Musculoskeletal
manned
NASA Discipline Number 00-00
Flight Experiment
STS-40 Shuttle Project

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