Document Detail

Mechanisms of activation of muscle branched-chain alpha-keto acid dehydrogenase during exercise in man.
MedLine Citation:
PMID:  8865084     Owner:  NLM     Status:  MEDLINE    
1. Exercise leads to activation (dephosphorylation) of the branched-chain alpha-keto acid dehydrogenase (BCKADH). Here we investigate the effect of low pre-exercise muscle glycogen content and of branched-chain amino acid (BCAA) ingestion on the activity of BCKADH at rest and after 90 min of one-leg knee-extensor exercise at 65% maximal one-leg power output in five subjects. 2. Pre-exercise BCAA ingestion (308 mg BCAAs (kg body wt)-1) caused an increased muscle BCAA uptake, a higher intramuscular BCAA concentration and activation of BCKADH both at rest (9 +/- 1 versus 25 +/- 5% for the control and BCAA test, respectively) and after exercise (27 +/- 4 versus 54 +/- 7%). 3. At rest the percentage active BCKADH was not different, 6 +/- 2% versus 5 +/- 1%, in the normal and low glycogen content leg (392 +/- 21 and 147 +/- 34 mumol glycosyl units (g dry muscle)-1, respectively). The post-exercise BCKADH activity was higher in the low (46 +/- 2%) than in the normal glycogen content leg (26 +/- 2%). 4. It is concluded that: (1) the mechanism of activation by BCAA ingestion probably involves an increase of the muscle BCAA concentration; (2) BCKADH activation caused by exercise and BCAA ingestion are additive; (3) low pre-exercise muscle glycogen content augments the exercise-induced BCKADH activation without an increase in muscle BCAA concentration; and (4) the mechanism of BCKADH activation via BCAA ingestion and low muscle glycogen content are different.
G van Hall; D A MacLean; B Saltin; A J Wagenmakers
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of physiology     Volume:  494 ( Pt 3)     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1996 Aug 
Date Detail:
Created Date:  1997-01-06     Completed Date:  1997-01-06     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  899-905     Citation Subset:  IM; S    
Department of Human Biology, University of Limburg, Maastricht, The Netherlands. G.vanHall@HB.RuLimburg.NL
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MeSH Terms
3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
Exercise / physiology*
Glycogen / metabolism*
Ketone Oxidoreductases / metabolism*
Knee / physiology*
Multienzyme Complexes / metabolism*
Muscle, Skeletal / metabolism*
Reg. No./Substance:
0/Multienzyme Complexes; 9005-79-2/Glycogen; EC 1.2.-/Ketone Oxidoreductases; EC Dehydrogenase (Lipoamide)

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