Creatine supplementation increases glycogen storage but not GLUT-4 expression in human skeletal muscle

van Loon, Luc J. C., Murphy, Robyn, Oosterlaar, Audrey M., Cameron-Smith, David, Hargreaves, Mark, Wagenmakers, Anton J. M. and Snow, Rodney 2004, Creatine supplementation increases glycogen storage but not GLUT-4 expression in human skeletal muscle, Clinical science, vol. 106, pp. 99-106.

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Title Creatine supplementation increases glycogen storage but not GLUT-4 expression in human skeletal muscle
Author(s) van Loon, Luc J. C.
Murphy, Robyn
Oosterlaar, Audrey M.
Cameron-Smith, David
Hargreaves, Mark
Wagenmakers, Anton J. M.
Snow, Rodney
Journal name Clinical science
Volume number 106
Start page 99
End page 106
Publisher Portland Press Ltd
Place of publication London, England
Publication date 2004-01
ISSN 0143-5221
1470-8736
Summary It has been speculated that creatine supplementation affects muscle glucose metabolism in humans by increasing muscle glycogen storage and up-regulating GLUT-4 protein expression. In the present study, we assessed the effects of creatine loading and prolonged supplementation on muscle glycogen storage and GLUT-4 mRNA and protein content in humans. A total of 20 subjects participated in a 6-week supplementation period during which creatine or a placebo was ingested. Muscle biopsies were taken before and after 5 days of creatine loading (20 g.day(-1)) and after 6 weeks of continued supplementation (2 g.day(-1)). Fasting plasma insulin concentrations, muscle creatine, glycogen and GLUT-4 protein content as well as GLUT-4, glycogen synthase-1 (GS-1) and glycogenin-1 (Gln-1) mRNA expression were determined. Creatine loading significantly increased total creatine, free creatine and creatine phosphate content with a concomitant 18 +/- 5% increase in muscle glycogen content (P<0.05). The subsequent use of a 2 g.day(-1) maintenance dose for 37 days did not maintain total creatine, creatine phosphate and glycogen content at the elevated levels. The initial increase in muscle glycogen accumulation could not be explained by an increase in fasting plasma insulin concentration, muscle GLUT-4 mRNA and/or protein content. In addition, neither muscle GS-1 nor Gln-1 mRNA expression was affected. We conclude that creatine ingestion itself stimulates muscle glycogen storage, but does not affect muscle GLUT-4 expression.
Language eng
Field of Research 060104 Cell Metabolism
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2004, Biochemical Society
Persistent URL http://hdl.handle.net/10536/DRO/DU:30008680

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