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Mechanical overload increases muscle mass but does not change myosin isoform expression in a rodent hibernator, Spermophilus lateralis
Author(s) -
Rourke Bryan,
Selpides PocholoJose,
Nowell Megan,
Rippen Marie,
Caiozzo Vincent J,
Baker Michael
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.754.23
Subject(s) - gene isoform , plantaris muscle , myosin , myostatin , medicine , biology , skeletal muscle , muscle atrophy , ground squirrel , endocrinology , citrate synthase , microbiology and biotechnology , soleus muscle , gene , biochemistry , enzyme , thermoregulation
Hibernating ground squirrels do not show slow to fast myosin heavy‐chain (MyHC) isoform transitions with atrophy, and we test whether increased muscle loading would also fail to produce typical MyHC isoform shifts. Field‐caught, Summer‐active ground squirrels ( Spermophilus lateralis ) were assessed for the responsiveness of hindlimb plantaris muscles to mechanical overload through synergist surgical ablation. Plantaris muscles of surgical animals were 40% larger than controls after 14 days, but did not show any of the expected shifts in MyHC isoform expression. We also measured MyHC isoform mRNA expression, citrate synthase activity, and the expression of a suite of genes involved in the control of skeletal muscle mass and MyHC isoform expression, including MAFbx, MuRF1, FOXO1, IGF1 and IGFBP5, and myostatin. Our results show an unusual insensitivity of hibernator muscles to mechanical overload induced isoform shifts, yet muscle mass was increased, which has implications for isoform expression and muscle adaptations during hibernation. Funding sources: NIH SCORE, NIH RISE, CSULB.