Document Detail

Effect of theophylline on substrate metabolism during exercise.
MedLine Citation:
PMID:  8781304     Owner:  NLM     Status:  MEDLINE    
We tested the hypothesis that adenosine is involved in regulating substrate metabolism during exercise. Seven trained cyclists were studied during 30 minutes of exercise at approximately 75% maximal oxygen uptake (VO2max). Lipid metabolism was evaluated by infusing [2H5]glycerol and [1-13C]palmitate, and glucose kinetics were evaluated by infusing [6,6-2H]glucose. Fat and carbohydrate oxidation were also measured by indirect calorimetry. The same subjects performed two identical exercise tests, but in one trial theophylline, a potent adenosine receptor antagonist, was infused for 1 hour before and throughout exercise. Theophylline did not increase whole-body lipolysis (glycerol rate of appearance [Ra]) or free fatty acid (FFA) release during exercise, but fat oxidation was lower than control values (9.5 +/- 3.0 v 18.0 +/- 4.2 micromol x min(-1) x kg(-1), P < .01). Glucose Ra was not affected by theophylline infusion, but glucose uptake was lower (31.6 +/- 4.1 v 40.4 +/- 5.0 micromol x min(-1) x kg(-1), P < .05) and glucose concentration was higher (6.4 +/- 0.6 v 5.8 +/- 0.4 mmol/L, P < .05) than in the control trial. Total carbohydrate oxidation (302.3 +/- 26.2 v 265.5 +/- 11.7 micromol x min(-1) x kg(-1), P < .06), estimated muscle glycogenolysis (270.7 +/- 23.1 v 225.1 +/- 9.7 micromol x min(-1) x kg(-1), P < .05), and plasma lactate concentration (7.9 +/- 1.6 v 5.9 +/- 1.1 mmol/L, P < .001) were also higher during the theophylline trial. These data suggest that adenosine may play a role in stimulating glucose uptake and restraining glycogenolysis but not in limiting lipolysis during exercise.
C A Raguso; A R Coggan; L S Sidossis; A Gastaldelli; R R Wolfe
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Metabolism: clinical and experimental     Volume:  45     ISSN:  0026-0495     ISO Abbreviation:  Metab. Clin. Exp.     Publication Date:  1996 Sep 
Date Detail:
Created Date:  1996-10-18     Completed Date:  1996-10-18     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0375267     Medline TA:  Metabolism     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1153-60     Citation Subset:  IM; S    
Metabolism Unit, Shriners Burns Institute, Galveston, TX 77550, USA.
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MeSH Terms
Blood Glucose / metabolism
Catecholamines / blood
Energy Metabolism
Exercise / physiology*
Glucagon / blood
Glucose / administration & dosage,  metabolism
Glycerol / administration & dosage,  blood
Glycogen / metabolism
Insulin / blood
Muscles / metabolism
Phosphodiesterase Inhibitors / pharmacology
Receptors, Purinergic P1 / antagonists & inhibitors
Theophylline / pharmacology*
Reg. No./Substance:
0/Blood Glucose; 0/Catecholamines; 0/Phosphodiesterase Inhibitors; 0/Receptors, Purinergic P1; 11061-68-0/Insulin; 50-99-7/Glucose; 56-81-5/Glycerol; 58-55-9/Theophylline; 9005-79-2/Glycogen; 9007-92-5/Glucagon

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