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rdf:type |
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lifeskim:mentions |
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pubmed:dateCreated |
1990-12-19
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pubmed:abstractText |
1. The rate constant of tension redevelopment (ktr) following a rapid release and subsequent re-extension of muscle length has been demonstrated to be Ca2+ sensitive and is thought to reflect the rate-limiting step in the cross-bridge cycle leading to the formation of the strongly bound, force-bearing state. The kinetics of this cross-bridge state transition were investigated at 15 degrees C over a wide range of Ca2+ concentrations while varying pH from 7.00 to 6.20 in rat slow-twitch soleus, rat fast-twitch superficial vastus lateralis (SVL) and rabbit fast-twitch psoas skinned single fibres. 2. At maximal levels of Ca2+ activation, ktr was unaffected by changes in pH from 7.00 to 6.20 while isometric tension was depressed to 0.60 +/- 0.02 P0 (mean +/- S.E.M.) at the low pH in fast-twitch fibres and to 0.78 +/- 0.01 P0 in slow-twitch fibres (P0 is the maximum isometric tension obtained at pH 7.00). 3. At reduced levels of Ca2+ activation, corresponding to pCa (-log [Ca2+]) greater than 5.0, ktr was markedly depressed in all fibre types when pH was lowered. The Ca2+ sensitivity of steady-state isometric tension was also reduced in all fibres at pH 6.20 compared to pH 7.00. 4. The results suggest that pH has a modulatory effect upon an apparent rate constant which is rate limiting in terms of the formation of the strongly bound, force-bearing cross-bridge state. This effect of altered pH may in part account for the reduction in the Ca2+ sensitivity of isometric force at low pH as well as the depression of the rate of rise of tension in living fibres during fatiguing stimulation.
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pubmed:grant |
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-1080798,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-13485191,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-156624,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2231431,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2309121,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2661721,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2726438,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2842489,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2939452,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2941026,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2952052,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2952054,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2966401,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-2969265,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-306438,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-308189,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-314975,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-3156404,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-3159090,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-3233271,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-3446809,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-34617,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-3563496,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-3597214,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-4253003,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2231432-7016549
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Sep
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pubmed:issn |
0022-3751
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
428
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
751-64
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:2231432-Animals,
pubmed-meshheading:2231432-Calcium,
pubmed-meshheading:2231432-Female,
pubmed-meshheading:2231432-Hydrogen-Ion Concentration,
pubmed-meshheading:2231432-Isometric Contraction,
pubmed-meshheading:2231432-Kinetics,
pubmed-meshheading:2231432-Male,
pubmed-meshheading:2231432-Muscles,
pubmed-meshheading:2231432-Rabbits,
pubmed-meshheading:2231432-Rats,
pubmed-meshheading:2231432-Rats, Inbred Strains
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pubmed:year |
1990
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pubmed:articleTitle |
pH modulation of the kinetics of a Ca2(+)-sensitive cross-bridge state transition in mammalian single skeletal muscle fibres.
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pubmed:affiliation |
Department of Physiology, School of Medicine, University of Wisconsin, Madison 53706.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, U.S. Gov't, P.H.S.
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