| Homogenization-dependent responses of acid-soluble and acid-insoluble glycogen to exercise and refeeding in human muscles. | |
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MedLine Citation:
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PMID: 19709696 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Muscle glycogen exists as acid-insoluble (AIG) and acid-soluble (ASG) forms, with AIG levels reported in most recent studies in humans to be the most responsive to exercise and refeeding. Because the muscle samples in these studies were not homogenized to extract glycogen, such homogenization-free protocols might have resulted in a suboptimal yield of ASG. Our goal, therefore, was to determine whether similar findings can be achieved using homogenized muscle samples by comparing the effect of exercise and refeeding on ASG and AIG levels. Eight male participants cycled for 60 minutes at 70% Vo(2peak) before ingesting 10.9 +/- 0.6 g carbohydrate per kilogram body mass over 24 hours. Muscle biopsies were taken before exercise and after 0, 2, and 24 hours of recovery. Using a homogenization-dependent protocol to extract glycogen, 77% to 91% of it was extracted as ASG, compared with 11% to 24% with a homogenization-free protocol. In response to exercise, muscle glycogen levels fell from 366 +/- 24 to 184 +/- 46 mmol/kg dry weight and returned to 232 +/- 32 and 503 +/- 59 mmol/kg dry weight after 2 and 24 hours, respectively. Acid-soluble glycogen but not AIG accounted for all the changes in total glycogen during exercise and refeeding when extracted using a homogenization-dependent protocol, but AIG was the most responsive fraction when extracted using a homogenization-free protocol. In conclusion, the patterns of response of ASG and AIG levels to changes in glycogen concentrations in human muscles are highly dependent on the protocol used to acid-extract glycogen, with the physiologic significance of the many previous studies on AIG and ASG being in need of revision. |
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Authors:
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Phillip D Barnes; Anish Singh; Paul A Fournier |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2009-08-25 |
Journal Detail:
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Title: Metabolism: clinical and experimental Volume: 58 ISSN: 1532-8600 ISO Abbreviation: Metab. Clin. Exp. Publication Date: 2009 Dec |
Date Detail:
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Created Date: 2009-11-16 Completed Date: 2009-11-30 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0375267 Medline TA: Metabolism Country: United States |
Other Details:
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Languages: eng Pagination: 1832-9 Citation Subset: IM |
Affiliation:
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School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, WA 6009, Australia. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Anaerobic Threshold
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physiology Eating / physiology* Exercise / physiology* Female Glycogen / chemistry, isolation & purification, metabolism* Humans Linear Models Male Muscle, Skeletal / metabolism* Young Adult |
| Chemical | |
Reg. No./Substance:
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9005-79-2/Glycogen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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