Document Detail

Influence of muscle glycogen content on metabolic regulation.
MedLine Citation:
PMID:  9458750     Owner:  NLM     Status:  MEDLINE    
Euglycemia was maintained in 13 subjects with low muscle glycogen [low glycogen, euglycemic (LGE), n = 8; low glycogen, euglycemic, hyperinsulinemic (LGEI), n = 5] and 6 subjects with normal muscle glycogen (NGE), whereas hyperglycemia was maintained in 8 low muscle glycogen subjects (LGH). All subjects cycled for 145 min at 70% of maximal oxygen uptake during the infusions. Insulin was infused in LGEI at 0.2 During exercise, respiratory exchange ratio (RER) was lower and norepinephrine higher in LGE than in NGE. In LGEI and LGH, RER at the start of exercise was the same as in LGE but did not decrease as in LGE. Free fatty acids (FFA) were higher and plasma insulin concentrations lower in LGE than NGE, LGEI, or LGH over the first 45 min of exercise. Rate of glucose infusion (Ri) and rate of glucose oxidation (Rox) were higher in LGH and LGEI than in NGE or LGE, and Ri matched Rox in all groups except LGH, in which Ri was greater than Rox. Muscle glycogen disappearance was greater in NGE than LGE, LGEI, or LGH, but the latter three groups did not differ. In conclusion, this study showed that low muscle glycogen content results in a decrease in RER, an increase in FFA, fat oxidation, and norepinephrine both at rest and during exercise, and does not affect Rox when euglycemia is maintained by infusion of glucose alone. Rox was increased only during insulin and hyperglycemia.
S M Weltan; A N Bosch; S C Dennis; T D Noakes
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  274     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1998 Jan 
Date Detail:
Created Date:  1998-02-19     Completed Date:  1998-02-19     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  E72-82     Citation Subset:  IM; S    
Department of Physiology, University of Cape Town Medical School, Observatory, South Africa.
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MeSH Terms
Blood Glucose / metabolism
Dietary Carbohydrates
Dietary Fats
Energy Intake
Energy Metabolism*
Exercise Test
Glucagon / blood,  secretion
Glucose Clamp Technique
Glycogen / metabolism*
Infusions, Intravenous
Insulin / administration & dosage,  pharmacology
Lactates / blood
Muscle Fatigue
Muscle, Skeletal / drug effects,  physiology*
Oxygen Consumption*
Physical Endurance / physiology*
Reg. No./Substance:
0/Blood Glucose; 0/Dietary Carbohydrates; 0/Dietary Fats; 0/Lactates; 11061-68-0/Insulin; 9005-79-2/Glycogen; 9007-92-5/Glucagon

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