Document Detail

Chronic low frequency stimulation reduces myosin phosphorylation in rabbit fast twitch muscle.
MedLine Citation:
PMID:  1330259     Owner:  NLM     Status:  MEDLINE    
The effect of 1-12 days of electrical stimulation (10 Hz) on the ability to phosphorylate the P-light chain of myosin was studied in rabbit tibialis anterior muscle. Myosin phosphorylation was induced by exposure of the stimulated muscle and that of the contralateral leg to a single conditioning stimulus train (5 Hz) for 25 s via the motor nerve. Isometric tension was measured as were the myosin light chain composition and the activities of the enzymes responsible for phosphorylation and dephosphorylation. A computer simulation of the potential effect of a stimulation-induced disruption of Ca2+ metabolism on phosphorylation was also performed. Chronic stimulation for as little as 1 day eliminated light chain phosphorylation and reduced the myosin light chain kinase activity by approximately 36%. Conversely, phosphatase activity and light chain composition were unaffected. The model demonstrated that a slight depression in the magnitude of the Ca2+ transient could potentially attenuate phosphorylation. The data suggest that phosphorylation of myosin is extremely sensitive to prolonged muscle activity. Furthermore, it appears more likely that this sensitivity is related to regulation of intracellular free Ca2+ than to the other elements of the calmodulin-dependent system for myosin phosphorylation examined.
G A Klug; M Biedermann; M E Houston; D Stuart; M Mumby; J T Stull
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Canadian journal of physiology and pharmacology     Volume:  70     ISSN:  0008-4212     ISO Abbreviation:  Can. J. Physiol. Pharmacol.     Publication Date:  1992 Jun 
Date Detail:
Created Date:  1992-12-23     Completed Date:  1992-12-23     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:  859-65     Citation Subset:  IM    
Department of Exercise and Movement Science, University of Oregon, Eugene 97403.
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MeSH Terms
Calcium / metabolism
Electric Stimulation
Isometric Contraction / physiology*
Muscle Tonus / physiology
Muscles / enzymology,  metabolism*,  physiology
Myosin-Light-Chain Kinase / metabolism
Myosin-Light-Chain Phosphatase
Myosins / metabolism*,  physiology
Phosphoprotein Phosphatases / metabolism
Time Factors
Grant Support
Reg. No./Substance:
7440-70-2/Calcium; EC Kinase; EC Phosphatases; EC Phosphatase; EC

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