| Effects of hypoxia on muscle protein synthesis (MPS) and anabolic signaling at rest and in response to acute resistance exercise. | |
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MedLine Citation:
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PMID: 21750270 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Background: Chronic reductions in tissue O(2) tension (hypoxia) are associated with muscle atrophy and blunted hypertrophic responses to resistance-exercise (RE) training. However, the effect of hypoxia on muscle protein synthesis (MPS) at rest and after RE is unknown. Methods: In a crossover study, seven healthy men (21.4±0.7 y) performed unilateral leg RE (6×8 repetitions at 70%-1RM) under normoxic (20.9% inspired O(2)) and normobaric hypoxic (12% inspired O(2) for 3.5 h) postabsorptive conditions. Immediately after RE the rested leg was biopsied and a primed-continuous infusion of [1,2-(13)C(2)]leucine was maintained for 2.5 h before final biopsies from both legs to measure tracer incorporation and signaling responses (i.e., ribosomal S6 kinase 1). Results: After 3.5 h hypoxia, MPS was not different from normoxia in the rest leg (normoxia 0.033±0.016 vs. hypoxia 0.043±0.016 %h.(-1)). MPS significantly increased from baseline 2.5 h after RE in normoxia (0.033±0.016 vs. 0.104±0.038 %h.(-1)) but not hypoxia (0.043±0.016 vs. 0.060 ± 0.063 %h.-1). A significant linear relationship existed between MPS 2.5 h after RE in hypoxia and mean arterial blood O(2) saturation during hypoxia (r(2)= 0.49; P= 0.04). Phosphorylation of p70S6K(Thr389) remained unchanged in hypoxia at rest but increased after RE in both normoxia and hypoxia (2.6±1.2-fold and 3.4±1.1-fold, respectively). Concentrations of the hypoxia responsive mTOR inhibitor, Regulated in Development and DNA damage-1 (REDD1) were unaltered by hypoxia or RE. Conclusion: Normobaric hypoxia does not reduce MPS over 3.5 h at rest but blunts the increased MPS response to acute RE to a degree dependent on extant SpO(2). |
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Authors:
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Timothy Etheridge; Philip J Atherton; Daniel Wilkinson; Anna Selby; Debbie Rankin; Nick Webborn; Kenneth Smith; Peter W Watt |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-7-12 |
Journal Detail:
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Title: American journal of physiology. Endocrinology and metabolism Volume: - ISSN: 1522-1555 ISO Abbreviation: - Publication Date: 2011 Jul |
Date Detail:
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Created Date: 2011-7-13 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901226 Medline TA: Am J Physiol Endocrinol Metab Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1University of Nottingham. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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