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Substrate oxidation capacity in rodent skeletal muscle: effects of exposure to zero gravityA study was conducted, as part of the integrated National Aeronautics and Space Administration Space Life Sciences 1 mission flown in June of 1991, to ascertain the effects of 9 days of exposure to zero gravity on the capacity of rodent skeletal muscle fiber types to oxidize either [14C]pyruvate or [14C]palmitate under state 3 metabolic conditions, i.e., nonlimiting amounts of substrate and cofactors. In addition, activity levels of marker enzymes of the tricarboxylic acid cycle, malate shuttle, and beta-oxidation were measured. Results showed that significant differences in muscle weight occurred in both the predominantly slow vastus intermedius and predominantly fast vastus lateralis of flight vs. control groups (P < 0.05). Total protein content of the muscle samples was similar between groups. Both pyruvate oxidation capacity and the marker oxidative enzymes were not altered in the flight relative to control animals. However, the capacity to oxidize long-chain fatty acids was significantly reduced by 37% in both the high- and low-oxidative regions of the vastus muscle (P < 0.05). Although these findings of a selective reduction in fatty acid oxidation capacity in response to spaceflight are surprising, they are consistent with previous findings showing 1) an increased capacity to take up glucose and upregulate glucose transporter proteins and 2) a marked accumulation of triglycerides in the skeletal muscles of rats subjected to states of unloading. Thus, skeletal muscle of animals exposed to non-weight-bearing environments undergo subcellular transformations that may preferentially bias energy utilization to carbohydrates.
Document ID
20050000415
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Baldwin, K. M.
(College of Medicine, University of California Irvine 92717)
Herrick, R. E.
McCue, S. A.
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
NASA Discipline Musculoskeletal
STS-40 Shuttle Project
NASA Program Flight
manned
NASA Discipline Number 00-00
Flight Experiment
Non-NASA Center
short duration
NASA Experiment Number 178127 1/3

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