Document Detail

Myosin phosphorylation, twitch potentiation, and fatigue in human skeletal muscle.
MedLine Citation:
PMID:  2383804     Owner:  NLM     Status:  MEDLINE    
Twitch tension and phosphate incorporation into the phosphorylatable light chains (P-light chains) of myosin were studied during a 10-min recovery period following a 10- or 60-s maximal voluntary isometric contraction (MVC) in 18 subjects. Analysis of muscle biopsy samples obtained before, immediately after, 1 min, and 10 min following the 10-s MVC revealed that the 10-s MVC produced a modest but transient metabolic displacement from rest, a 35% decrease in phosphocreatine, and a threefold elevation in lactate concentration. Immediately after the 60-s MVC, ATP was decreased by 20%, phosphocreatine decreased by 84%, and lactate was elevated by 15-fold. Lactate remained elevated over the 10-min recovery period. Twitch force was maximally potentiated following the 10-s MVC and declined to rest by 10 min of recovery. Twitch force was 0.66 of rest value immediately after the 60-s MVC, then increased over the next 4 min to reach a potentiated value 21% greater than rest, before declining. Significant phosphate incorporation into P-light chains was observed immediately after both contractions, but dephosphorylation to rest values at the end of recovery was only noted for the 60-s condition. These results demonstrate an inconsistent relationship between twitch tension enhancement and P-light chain phosphorylation in the in vivo human model.
M E Houston; R W Grange
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Canadian journal of physiology and pharmacology     Volume:  68     ISSN:  0008-4212     ISO Abbreviation:  Can. J. Physiol. Pharmacol.     Publication Date:  1990 Jul 
Date Detail:
Created Date:  1990-09-20     Completed Date:  1990-09-20     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0372712     Medline TA:  Can J Physiol Pharmacol     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  908-13     Citation Subset:  IM    
Department of Kinesiology, University of Waterloo, Ont., Canada.
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MeSH Terms
Adenosine Triphosphate / metabolism
Electric Stimulation
Glycogen / metabolism
Isometric Contraction
Lactates / metabolism
Muscle Contraction*
Muscles / metabolism,  physiology*
Myosins / metabolism*
Phosphates / metabolism
Phosphocreatine / metabolism
Reg. No./Substance:
0/Lactates; 0/Phosphates; 56-65-5/Adenosine Triphosphate; 67-07-2/Phosphocreatine; 9005-79-2/Glycogen; EC

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

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