HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/6/E1815    most recent 00598.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Wilson, R. J. Articles by Graham, T. E. Search for Related Content PubMed PubMed Citation Articles by Wilson, R. J. Articles by Graham, T. E.

Glycogenin protein and mRNA expression in response to changing glycogen concentration in exercise and recovery

Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada

Submitted 9 November 2006 ; accepted in final form 16 February 2007

Glycogenin (GN-1) is essential for the formation of a glycogen granule; however, rarely has it been studied when glycogen concentration changes in exercise and recovery. It is unclear whether GN-1 is degraded or is liberated and exists as apoprotein (apo)-GN-1 (unglycosylated). To examine this, we measured GN-1 protein and mRNA level at rest, at exhaustion (EXH), and during 5 h of recovery in which the rate of glycogen restoration was influenced by carbohydrate (CHO) provision. Ten males cycled (65% O_{2 max}) to volitional EXH (117.8 ± 4.2 min) on two separate occasions. Subjects were administered carbohydrate (CHO; 1 g·kg^–1·h^–1 Gatorlode) or water [placebo (PL)] during 5 h of recovery. Muscle biopsies were taken at rest, at EXH, and following 30, 60, 120, and 300 min of recovery. At EXH, total glycogen concentration was reduced (P < 0.05). However, GN-1 protein and mRNA content did not change. By 5 h of recovery, glycogen was resynthesized to 60% of rest in the CHO trial and remained unchanged in the PL trial. GN-1 protein and mRNA level did not increase during recovery in either trial. We observed modest amounts of apo-GN-1 at EXH, suggesting complete degradation of some granules. These data suggest that GN-1 is conserved, possibly as very small, or nascent, granules when glycogen concentration is low. This would provide the ability to rapidly restore glycogen during early recovery.

skeletal muscle; carbohydrate; exhaustion; resynthesis; recovery

This article has been cited by other articles:

				S. Roy, S. Khanna, C. Rink, S. Biswas, and C. K. Sen Characterization of the acute temporal changes in excisional murine cutaneous wound inflammation by screening of the wound-edge transcriptome Physiol Genomics, July 1, 2008; 34(2): 162 - 184. [Abstract] [Full Text] [PDF]