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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
Pt 3
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pubmed:dateCreated |
2002-12-16
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pubmed:abstractText |
The influence of Ca(2+)-activated force, the rate of dissociation of Ca(2+) from troponin C (TnC) and decreased crossbridge detachment rate on the time course of relaxation induced by flash photolysis of diazo-2 in rabbit skinned psoas fibres was investigated at 15 degrees C. The rate of relaxation increased as the diazo-2 chelating capacity (i.e. free [diazo-2]/free [Ca(2+)]) increased. At a constant diazo-2 chelating capacity, the rate of relaxation was independent of the pre-photolysis Ca(2+)-activated force in the range 0.3-0.8 of maximum isometric force. A TnC mutant that exhibited increased Ca(2+) sensitivity caused by a decreased Ca(2+) dissociation rate in solution (M82Q TnC) also increased the Ca(2+) sensitivity of steady-state force and decreased the rate of relaxation in fibres by approximately twofold. In contrast, a TnC mutant with decreased Ca(2+) sensitivity caused by an increased Ca(2+) dissociation rate in solution (NHdel TnC) decreased the Ca(2+) sensitivity of steady-state force but did not accelerate relaxation. Decreasing the rate of crossbridge kinetics by reducing intracellular inorganic phosphate concentration ([P(i)]) slowed relaxation by approximately twofold and led to two phases of relaxation, a slow linear phase followed by a fast exponential phase. In fibres, M82Q TnC further slowed relaxation in low [P(i)] conditions by approximately twofold, whereas NHdel TnC had no significant effect on relaxation. These results are consistent with the interpretation that the Ca(2+)-dissociation rate and crossbridge detachment rate are similar in fast-twitch skeletal muscle, such that decreasing either rate slows relaxation, but accelerating Ca(2+) dissociation has little effect on relaxation.
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pubmed:grant |
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-10049329,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-10226156,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-10233080,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-10827985,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-11076523,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-12324431,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-1491071,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-1633166,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-1816377,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-2243087,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-2661721,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-2966401,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-2969265,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-3654633,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-7053370,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-7758157,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-8031761,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-8132628,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-8195134,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-9176158,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-9449336,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-9449337,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-9578546,
http://linkedlifedata.com/resource/pubmed/commentcorrection/12482894-9611126
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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 |
Dec
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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:day |
15
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pubmed:volume |
545
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
887-901
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:12482894-Animals,
pubmed-meshheading:12482894-Binding, Competitive,
pubmed-meshheading:12482894-Calcium,
pubmed-meshheading:12482894-Chelating Agents,
pubmed-meshheading:12482894-Diazonium Compounds,
pubmed-meshheading:12482894-Female,
pubmed-meshheading:12482894-Histological Techniques,
pubmed-meshheading:12482894-Isometric Contraction,
pubmed-meshheading:12482894-Kinetics,
pubmed-meshheading:12482894-Muscle, Skeletal,
pubmed-meshheading:12482894-Muscle Fibers, Skeletal,
pubmed-meshheading:12482894-Muscle Relaxation,
pubmed-meshheading:12482894-Mutation,
pubmed-meshheading:12482894-Phenoxyacetates,
pubmed-meshheading:12482894-Photolysis,
pubmed-meshheading:12482894-Rabbits,
pubmed-meshheading:12482894-Time Factors,
pubmed-meshheading:12482894-Troponin C
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pubmed:year |
2002
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pubmed:articleTitle |
Determinants of relaxation rate in rabbit skinned skeletal muscle fibres.
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pubmed:affiliation |
Department of Physiology and Cell Biology, Ohio State University, 1645 Neil Ave., Columbus, OH 43210 USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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