Document Detail


Control of exercise-stimulated muscle glucose uptake by GLUT4 is dependent on glucose phosphorylation capacity in the conscious mouse.
MedLine Citation:
PMID:  15456776     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Previous work suggests that normal GLUT4 content is sufficient for increases in muscle glucose uptake (MGU) during exercise because GLUT4 overexpression does not increase exercise-stimulated MGU. Instead of glucose transport, glucose phosphorylation is a primary limitation of exercise-stimulated MGU. It was hypothesized that a partial ablation of GLUT4 would not impair exercise-stimulated MGU when glucose phosphorylation capacity is normal but would do so when glucose phosphorylation capacity was increased. Thus, C57BL/6J mice with hexokinase II (HKII) overexpression (HK(Tg)), a GLUT4 partial knock-out (G4(+/-)), or both (HK(Tg) + G4(+/-)) and wild-type (WT) littermates were implanted with carotid artery and jugular vein catheters for sampling and infusions at 4 months of age. After a 7-day recovery, 5-h fasted mice remained sedentary or ran on a treadmill at 0.6 mph for 30 min (n = 9-12 per group) and received a bolus of 2-deoxy[3H]glucose to provide an index of MGU (Rg). Arterial blood glucose and plasma insulin concentrations were similar in WT, G4(+/-), HKTg, and HKTg + G4(+/-) mice. Sedentary Rg values were the same in all genotypes in all muscles studied, confirming that glucose transport is a significant barrier to basal glucose uptake. Gastrocnemius and soleus Rg were greater in exercising compared with sedentary mice in all genotypes. During exercise, G4(+/-) mice had a marked increase in blood glucose that was corrected by the addition of HK II overexpression. Exercise Rg (micromol/100g/min) was not different between WT and G4(+/-) mice in the gastrocnemius (24 +/- 5 versus 21 +/- 2) or the soleus (54 +/- 6 versus 70 +/- 7). In contrast, the enhanced exercise Rg observed in HKTg mice compared with that in WT mice was absent in HKTg + G4(+/-) mice in both the gastrocnemius (39 +/- 7 versus 22 +/- 6) and the soleus (98 +/- 13 versus 65 +/- 13). Thus, glucose transport is not a significant barrier to exercise-stimulated MGU despite a 50% reduction in GLUT4 content when glucose phosphorylation capacity is normal. However, when glucose phosphorylation capacity is increased by HK II overexpression, GLUT4 availability becomes a marked limitation to exercise-stimulated MGU.
Authors:
Patrick T Fueger; Holli S Hess; Kelly A Posey; Deanna P Bracy; R Richard Pencek; Maureen J Charron; David H Wasserman
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.     Date:  2004-09-28
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  279     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2004 Dec 
Date Detail:
Created Date:  2004-11-25     Completed Date:  2005-01-11     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  50956-61     Citation Subset:  IM    
Affiliation:
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA. patrick.fueger@duke.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Biological Transport
Blood Glucose / metabolism
Cell Membrane / metabolism
Densitometry
Genotype
Glucose / metabolism*,  pharmacokinetics*
Glucose Transporter Type 4
Glycogen / metabolism
Heterozygote
Hexokinase / metabolism
Immunoblotting
Insulin / blood
Kinetics
Male
Mice
Mice, Inbred C57BL
Mice, Knockout
Mice, Transgenic
Monosaccharide Transport Proteins / metabolism*
Muscle Proteins / metabolism*
Muscle, Skeletal / metabolism*
Muscles / metabolism
Phosphorylation
Physical Conditioning, Animal
Time Factors
Grant Support
ID/Acronym/Agency:
R01 DK-47425/DK/NIDDK NIH HHS; R01 DK-54902/DK/NIDDK NIH HHS; U24 DK-59637/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Blood Glucose; 0/Glucose Transporter Type 4; 0/Monosaccharide Transport Proteins; 0/Muscle Proteins; 0/Slc2a4 protein, mouse; 11061-68-0/Insulin; 50-99-7/Glucose; 9005-79-2/Glycogen; EC 2.7.1.1/Hexokinase

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


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