Mechanosensitivity may be enhanced in skeletal muscles of spinal cord–injured versus able-bodied men

Authors

  • Ceren Yarar-Fisher PT, PhD,

    1. Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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  • C. Scott Bickel PT, PhD,

    1. Department of Physical Therapy, University of Alabama at Birmingham, Birmingham, Alabama, USA
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  • Neil A. Kelly MS,

    1. Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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  • Samuel T. Windham MD,

    1. Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, USA
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  • Amie B. Mclain MD,

    1. Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham, Birmingham, Alabama, USA
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  • Marcas M. Bamman PhD

    Corresponding author
    1. Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
    • Correspondence to: M.M. Bamman, UAB Center for Exercise Medicine, 966 McCallum Basic Health Sciences Building, 1720 Second Avenue South, University of Alabama at Birmingham, Birmingham, AL 35294-0005; e-mail: mbamman@uab.edu

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  • This work was supported by a VA Merit Award (to M.M.B.); the UAB Center for Exercise Medicine, Department of Physical Medicine and Rehabilitation (5T32 DK62710); and the UAB Center for Clinical and Translational Science (UL1 TR000165).

ABSTRACT

We investigated the effects of an acute bout of neuromuscular electrical stimulation–induced resistance exercise (NMES-RE) on intracellular signaling pathways involved in translation initiation and mechanical loading–induced muscle hypertrophy in spinal cord–injured (SCI) versus able-bodied (AB) individuals. AB and SCI individuals completed 90 isometric knee extension contractions at 30% of maximum voluntary or evoked contraction, respectively. Muscle biopsies were collected before, and 10 and 60 min after NMES-RE. Protein levels of α7- and β1-integrin, phosphorylated and total GSK-3α/β, S6K1, RPS6, 4EBP1, and FAK were assessed by immunoblotting. SCI muscle appears to be highly sensitive to muscle contraction even several years after the injury, and in fact it may be more sensitive to mechanical stress than AB muscle. Heightened signaling associated with muscle mechanosensitivity and translation initiation in SCI muscle may be an attempted compensatory response to offset elevated protein degradation in atrophied SCI muscle. Muscle Nerve 50: 599–601, 2014

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