Document Detail


Ca2+-activated myosin-ATPases, creatine and adenylate kinases regulate mitochondrial function according to myofibre type in rabbit.
MedLine Citation:
PMID:  15731190     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Mitochondrial respiration rates and their regulation by ADP, AMP and creatine, were studied at different free Ca(2+) concentrations (0.1 versus 0.4 microm) on permeabilized fibre bundles of rabbit skeletal muscles differing in their myosin heavy chain profiles. Four fibre bundle types were obtained: pure types I and IIx, and mixed types IIax (approximately 50% IIa and 50% IIx fibres) and IIb+ (60% IIb fibres, plus IIx and IIa). At rest, pure type I fibres displayed a much higher apparent K(m) for ADP (212 microm) than IIx fibres (8 microm). Within the IIax and IIb+ mixed fibre bundle types, two K(ADP)(m) values were observed (70 microm and 5 microm). Comparison between pure IIx and mixed types indicates that the intermediate K(m) of 70 microm most probably corresponds to the mitochondrial affinity for ADP in IIa fibres, the lowest K(m) for ADP (5 microm) corresponding to IIx and IIb types. Activation of mitochondrial creatine and adenylate kinase reactions stimulated mitochondrial respiration only in type I and IIax fibre bundles, indicating an efficient coupling between both kinases and ADP rephosphorylation in type I and, likely, IIa fibres, since no effect was observed in pure IIx fibres. Following Ca(2+)-induced activation of myosin-ATPase, an increase in mitochondrial sensitivity to ADP of 45% and 250% was observed in type IIax and I bundles, respectively, an effect mostly prevented by addition of vanadate, an inhibitor of myosin-ATPase. Ca(2+)-induced activation of myosin-ATPase also prevented the stimulation of respiration rates by creatine and AMP in I and IIax bundles. In addition to differential regulation of mitochondrial respiration and energy transfer systems at rest in I and IIa versus IIx and IIb muscle fibres, our results indicate a regulation of phosphotransfer systems by Ca(2+) via the stimulation of myosin-ATPases in type I and IIa fibres of rabbit muscles.
Authors:
N Gueguen; L Lefaucheur; P Ecolan; M Fillaut; P Herpin
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-02-24
Journal Detail:
Title:  The Journal of physiology     Volume:  564     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-05-16     Completed Date:  2005-08-11     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  723-35     Citation Subset:  IM    
Affiliation:
INRA, Unité Mixte de Recherche Système d'Elevage Nutrition Animale et Humaine, Domaine de la Prise, 35590 Saint-Gilles, France.
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MeSH Terms
Descriptor/Qualifier:
Adenylate Kinase / metabolism*
Animals
Calcium / metabolism*
Cell Respiration / physiology*
Cells, Cultured
Creatine Kinase / metabolism*
Energy Transfer / physiology
Enzyme Activation
Male
Mitochondria, Muscle / metabolism*
Muscle Fibers, Skeletal / metabolism*
Muscle, Skeletal / metabolism
Myosins / metabolism*
Rabbits
Chemical
Reg. No./Substance:
7440-70-2/Calcium; EC 2.7.3.2/Creatine Kinase; EC 2.7.4.3/Adenylate Kinase; EC 3.6.4.1/Myosins
Comments/Corrections
Comment In:
J Physiol. 2005 Jun 1;565(Pt 2):703; author reply 704   [PMID:  15932897 ]

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