| Ca(2+)-dependent heat production under basal and near-basal conditions in the mouse soleus muscle. | |
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MedLine Citation:
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PMID: 1484367 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. The rate of energy expended for the clearance of sarcoplasmic Ca2+ by sarcoreticular Ca2+ uptake process(es), plus the concomitant metabolic reactions, was evaluated from measurements of resting heat production by mouse soleus muscle before and after indirect inhibition of Ca2+ uptake by sarcoplasmic reticulum (SR). 2. Direct inhibition of the Ca2+, Mg(2+)-ATPase of SR membrane in intact muscle preparations exposed to the specific inhibitor 2,5-di(tert-butyl-1,4-benzohydroquinone (tBuBHQ) slowly increased the rate of heat production (E). Indirect inhibition of SR Ca2+ uptake was obtained by reducing sarcoplasmic Ca2+ concentration (Ca2+i) as a consequence of reducing Ca2+ release from the SR using dantrolene sodium. This promptly decreased E by 12%. Exposure of the preparations to an Mg(2+)-enriched environment (high Mg2+) or to the chemical phosphatase 2,3-butanedione monoxime (BDM), two other procedures aimed at decreasing SR Ca2+ release, also acutely decreased E, by 20 and 24%, respectively. 3. Subthreshold-for-contracture depolarization of the sarcolemma achieved by increasing extracellular K+ concentration to 11.8 mM induced a biphasic increase of E: an initial peak to 290% of basal E, followed by a plateau phase at 140% of basal E during which resting muscle tension was increased by less than 3%. Most, if not all, of the plateau-phase metabolic response was quickly suppressed by dantrolene or high Mg2+ or BDM. Another means of increasing SR Ca2+ cycling was to partially remove the calmodulin-dependent control of SR Ca2+ release using the calmodulin inhibitor W-7. The progressive increase in E with 30 microM-W-7 was largely reduced by dantrolene or high Mg2+ or BDM. 4. In the presence of either dantrolene or BDM to prevent the effect of W-7 on SR Ca2+ release, exposure of the muscle to W-7 acutely suppressed about 3% of E. This and the above results confirm that the plasmalemmal, calmodulin-dependent Ca(2+)-ATPase, although a qualitatively essential part of the Ca2+i homeostatic system of the cell, can only be responsible for a very minor part of the energy expenditure devoted to the homeostasis of Ca2+i. Active Ca2+ uptake by SR which, at least in the submicromolar range of Ca2+i, is expected to be responsible for most of this Ca(2+)-dependent energy expenditure, might dissipate up to 25-40% of total metabolic energy in the intact mouse soleus under basal and near-basal conditions. |
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Authors:
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A Chinet; A Decrouy; P C Even |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of physiology Volume: 455 ISSN: 0022-3751 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 1992 Sep |
Date Detail:
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Created Date: 1993-02-17 Completed Date: 1993-02-17 Revised Date: 2010-09-07 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 663-78 Citation Subset: IM |
Affiliation:
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Department of Physiology, University of Geneva, Switzerland. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Basal Metabolism Body Temperature Regulation / physiology* Calcium / metabolism* Calmodulin / antagonists & inhibitors Dantrolene / pharmacology Diacetyl / analogs & derivatives, pharmacology Energy Metabolism / physiology* Ethylmaleimide / pharmacology Homeostasis Hydroquinones / pharmacology Mice Muscles / metabolism* Oxygen Consumption / physiology Sarcoplasmic Reticulum / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Calmodulin; 0/Hydroquinones; 128-53-0/Ethylmaleimide; 431-03-8/Diacetyl; 57-71-6/diacetylmonoxime; 7261-97-4/Dantrolene; 7440-70-2/Calcium; 88-58-4/2,5-di-tert-butylhydroquinone |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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