Document Detail

Role of superficially membrane-bound calcium on excitation-contraction coupling in frog skeletal muscle.
MedLine Citation:
PMID:  966398     Owner:  NLM     Status:  MEDLINE    
Single fibers isolated from frog semitendinosus muscle continued to twitch for 5-8 min in calcium-free Ringer solution containing 1 mM ethylene glycol bis (beta-aminoethyl ether)-N, N'-tetraacetic acid (EGTA). Even after twitching was completely abolished, the tension of potassium contracture was not depressed, although the time course was markedly shortened. The resting potential recorded from single fibers 10 min after immersion in EGTA-Ringer solution decreased slightly. These fibers failed to generate action potential, however, in a whole sartorius muscle the self-exchangeable calcium was not significantly reduced by 1mM EGTA, while it was reduced by about 27% during the potassium contracture induced in the EGTA solution. From these results, it is suggested that the calcium bound on the surface sites of the transverse tubular membrane and the sarcolemma can serve as a trigger for the release of calcium from the sarcoplasmic reticulum and can produce a resting potential and maintain relatively long duration excitability under the condition of extracellular calcium deficiency.
I Oota; I Kosaka; T Nagai
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  The Japanese journal of physiology     Volume:  26     ISSN:  0021-521X     ISO Abbreviation:  Jpn. J. Physiol.     Publication Date:  1976  
Date Detail:
Created Date:  1976-11-21     Completed Date:  1976-11-21     Revised Date:  2007-03-21    
Medline Journal Info:
Nlm Unique ID:  2985184R     Medline TA:  Jpn J Physiol     Country:  JAPAN    
Other Details:
Languages:  eng     Pagination:  117-26     Citation Subset:  IM    
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MeSH Terms
Action Potentials*
Calcium / physiology*
Cations, Divalent
Electric Stimulation
Muscle Contraction*
Muscles / physiology*
Potassium / physiology
Reg. No./Substance:
0/Cations, Divalent; 7440-09-7/Potassium; 7440-70-2/Calcium

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

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