title: Mechanosensitivity may be enhanced in skeletal muscles of spinal cord-injured versus able-bodied men.
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. .
authors.affiliation: Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: Ceren
authors.initials: C
authors.lastname: Yarar-Fisher
authors.forename: C Scott
authors.initials: CS
authors.lastname: Bickel
authors.forename: Neil A
authors.initials: NA
authors.lastname: Kelly
authors.forename: Samuel T
authors.initials: ST
authors.lastname: Windham
authors.forename: Amie B
authors.initials: AB
authors.lastname: Mclain
authors.forename: Marcas M
authors.initials: MM
authors.lastname: Bamman
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000328:Adult; D000704:Analysis of Variance; D018797:Cell Cycle Proteins; D004599:Electric Stimulation Therapy / Q000379:methods*; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D006801:Humans; D039641:Integrin beta Chains / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010750:Phosphoproteins / Q000378:metabolism; D038601:Ribosomal Protein S6 / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000473:pathology* / Q000534:rehabilitation*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C087000:EIF4EBP1 protein, human; D039641:Integrin beta Chains; D010750:Phosphoproteins; D038601:Ribosomal Protein S6; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D038362:Glycogen Synthase Kinase 3
keywords: mechanotransduction; neuromuscular electrical stimulation; resistance exercise; skeletal muscle; spinal cord injury