Document Detail

Skeletal muscle malonyl-CoA content at the onset of exercise at varying power outputs in humans.
MedLine Citation:
PMID:  9611159     Owner:  NLM     Status:  MEDLINE    
To investigate the regulation of intramuscular fuel selection, we measured the malonyl-CoA (M-CoA) content in human skeletal muscle at three exercise power outputs [35, 65, and 90% maximal rate of O2 consumption (VO2 max)]. Four males and four females cycled for 10 min at one power output on three separate occasions with muscle biopsies sampled at rest and at 1 and 10 min. The respiratory exchange ratio was 0.84 +/- 0.03, 0.92 +/- 0.02, and >1.0 at 35, 65 and 90% VO2 max, respectively. Muscle lactate content increased and phosphocreatine content decreased as a function of power output. Pyruvate dehydrogenase a activity increased from 0.40-0.64 mmol . kg wet muscle-1 . min-1 at rest to 1.57 +/- 0.28, 2.80 +/- 0.41, and 3. 28 +/- 0.27 mmol . kg wet muscle-1 . min-1 after 1 min of cycling at the three power outputs, respectively. Mean resting M-CoA contents were similar at all power outputs (1.85-1.98 micromol/kg dry muscle). During exercise at 35% VO2 max, M-CoA decreased from rest at 1 min (1.85 +/- 0.29 to 1.20 +/- 0.12 micromol/kg dry muscle) but returned to rest level by 10 min (1.86 +/- 0.25 micromol/kg dry muscle). M-CoA content did not decrease during cycling at 65% VO2 max. At 90% VO2 max, M-CoA did not increase despite significant acetyl-CoA accumulation (the substrate for M-CoA synthesis). The data suggest that a decrease in M-CoA content is not required for the increase in free fatty acid uptake and oxidation that occurs during exercise at 35 and 65% VO2 max. Furthermore, M-CoA content does not increase during exercise at 90% VO2 max and does not contribute to the lower rate of fat oxidation at this power output.
L M Odland; R A Howlett; G J Heigenhauser; E Hultman; L L Spriet
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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 Jun 
Date Detail:
Created Date:  1998-08-06     Completed Date:  1998-08-06     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:  E1080-5     Citation Subset:  IM; S    
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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MeSH Terms
Adenosine Triphosphate / metabolism
Exercise / physiology*
Fatty Acids, Nonesterified / metabolism
Glucose / metabolism
Lactic Acid / metabolism
Malonyl Coenzyme A / metabolism*
Muscle, Skeletal / metabolism*
Oxygen Consumption*
Phosphocreatine / metabolism
Pulmonary Gas Exchange
Pyruvate Dehydrogenase Complex / metabolism
Reg. No./Substance:
0/Fatty Acids, Nonesterified; 0/Pyruvate Dehydrogenase Complex; 50-21-5/Lactic Acid; 50-99-7/Glucose; 524-14-1/Malonyl Coenzyme A; 56-65-5/Adenosine Triphosphate; 67-07-2/Phosphocreatine

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