Document Detail


Proglycogen and macroglycogen: artifacts of glycogen extraction?
MedLine Citation:
PMID:  18328357     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Most recent studies on the physiology of proglycogen and macroglycogen in skeletal muscles have adopted a homogenization-free acid extraction protocol to separate these 2 pools of glycogen. The purposes of this study were to determine (a) whether this protocol is suitable; (b) if the acid-insoluble glycogen fraction corresponds to proglycogen; and (c) if this fraction accounts for most of the changes in muscle glycogen content, irrespective of muscle fiber types. Using the rat as our experimental model, this study shows that when the conditions of acid extraction are optimized, 52% to 64% of glycogen in rat muscles is found as acid-soluble glycogen as opposed to approximately 16% when glycogen is extracted using a homogenization-free extraction protocol. Moreover, there is no evidence that the acid-insoluble glycogen corresponds to proglycogen because gel chromatography of the acid-insoluble and acid-soluble glycogen fractions shows similar elution profiles of high-molecular weight glycogen. Finally, irrespective of muscle fiber types, the acid-soluble glycogen accounts for most of the changes in total muscle glycogen levels during the fasting-to-fed transition, whereas the levels of the acid-insoluble glycogen remain stable or increase marginally. In conclusion, this study shows that the homogenization-free acid extraction of muscle glycogen underestimates the proportion of acid-soluble glycogen and that the findings of the studies that have adopted such an extraction protocol to examine the physiology of acid-insoluble and acid-soluble glycogens require reexamination.
Authors:
Anthony P James; Phillip D Barnes; T Norman Palmer; Paul A Fournier
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Metabolism: clinical and experimental     Volume:  57     ISSN:  0026-0495     ISO Abbreviation:  Metab. Clin. Exp.     Publication Date:  2008 Apr 
Date Detail:
Created Date:  2008-03-10     Completed Date:  2008-04-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375267     Medline TA:  Metabolism     Country:  United States    
Other Details:
Languages:  eng     Pagination:  535-43     Citation Subset:  IM    
Affiliation:
School of Public Health, Curtin University of Technology, Bentley, Western Australia 6102, Australia.
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MeSH Terms
Descriptor/Qualifier:
Animals
Chromatography, Gel
Fasting
Glycogen / metabolism*
Male
Molecular Weight
Muscle, Skeletal / metabolism*
Rats
Rats, Wistar
Chemical
Reg. No./Substance:
9005-79-2/Glycogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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