| Skeletal Muscle Amino Acid Transporter Expression is Increased in Young and Older Adults Following Resistance Exercise. | |
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MedLine Citation:
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PMID: 21527663 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Amino acid transporters and mTORC1 signaling are important contributors to muscle protein anabolism. Aging is associated with reduced mTORC1 signaling following resistance exercise, but the role of amino acid transporters is unknown. Young (n=13; 28±2y) and older (n=13; 68±2y) subjects performed a bout of resistance exercise. Skeletal muscle biopsies (vastus lateralis) were obtained at Basal, 3, 6, and 24h post-exercise and were analyzed for amino acid transporter mRNA and protein expression and regulators of amino acid transporter transcription utilizing real-time PCR and western blotting. We found that basal amino acid transporter expression was similar in young and older adults (P>0.05). Exercise increased LAT1/SLC7A5, CD98/SLC3A2, SNAT2/SLC38A2, PAT1/SLC36A1, and CAT1/SLC7A1 mRNA expression in both young and older adults (P<0.05). LAT1 and CD98 protein increased only in younger adults (P<0.05). eIF2α (S52) increased similarly in young and older adults post-exercise (P<0.05). rpS6 (S240/244) and ATF4 nuclear protein expression tended to be higher in the young while nuclear STAT3 (Y705) was higher in the older subjects post-exercise (P<0.05). These results suggest that the rapid upregulation of amino acid transporter expression following resistance exercise may be regulated differently between the age groups and involves a combination of mTORC1, ATF4, eIF2α, and STAT3. We propose an increase in amino acid transporter expression may contribute to enhanced amino acid sensitivity following exercise in young and older adults. In older adults, the increased nuclear STAT3 phosphorylation may be indicative of an exercise-induced stress response perhaps to export amino acids from muscle cells. |
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Authors:
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Micah J Drummond; Christopher S Fry; Erin L Glynn; Kyle Lee Timmerman; Jared M Dickinson; Dillon K Walker; David M Gundermann; Elena Volpi; Blake B Rasmussen |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-4-28 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: - Publication Date: 2011 Apr |
Date Detail:
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Created Date: 2011-4-29 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1University of Texas Medical Branch. |
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