| The dynamics of mitochondrial Ca2+ fluxes. | |
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MedLine Citation:
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PMID: 20599532 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We have investigated the kinetics of mitochondrial Ca(2+) influx and efflux and their dependence on cytosolic [Ca(2+)] and [Na(+)] using low-Ca(2+)-affinity aequorin. The rate of Ca(2+) release from mitochondria increased linearly with mitochondrial [Ca(2+)] ([Ca(2+)](M)). Na(+)-dependent Ca(2+) release was predominant al low [Ca(2+)](M) but saturated at [Ca(2+)](M) around 400muM, while Na(+)-independent Ca(2+) release was very slow at [Ca(2+)](M) below 200muM, and then increased at higher [Ca(2+)](M), perhaps through the opening of a new pathway. Half-maximal activation of Na(+)-dependent Ca(2+) release occurred at 5-10mM [Na(+)], within the physiological range of cytosolic [Na(+)]. Ca(2+) entry rates were comparable in size to Ca(2+) exit rates at cytosolic [Ca(2+)] ([Ca(2+)](c)) below 7muM, but the rate of uptake was dramatically accelerated at higher [Ca(2+)](c). As a consequence, the presence of [Na(+)] considerably reduced the rate of [Ca(2+)](M) increase at [Ca(2+)](c) below 7muM, but its effect was hardly appreciable at 10muM [Ca(2+)](c). Exit rates were more dependent on the temperature than uptake rates, thus making the [Ca(2+)](M) transients to be much more prolonged at lower temperature. Our kinetic data suggest that mitochondria have little high affinity Ca(2+) buffering, and comparison of our results with data on total mitochondrial Ca(2+) fluxes indicate that the mitochondrial Ca(2+) bound/Ca(2+) free ratio is around 10- to 100-fold for most of the observed [Ca(2+)](M) range and suggest that massive phosphate precipitation can only occur when [Ca(2+)](M) reaches the millimolar range. |
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Authors:
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Sergio de la Fuente; Pablo Montenegro; Rosalba I Fonteriz; Alfredo Moreno; Carmen D Lobatón; Mayte Montero; Javier Alvarez |
Publication Detail:
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Type: Journal Article Date: 2010-06-25 |
Journal Detail:
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Title: Biochimica et biophysica acta Volume: 1797 ISSN: 0006-3002 ISO Abbreviation: Biochim. Biophys. Acta Publication Date: 2010 Oct |
Date Detail:
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Created Date: 2010-08-13 Completed Date: 2010-10-28 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0217513 Medline TA: Biochim Biophys Acta Country: Netherlands |
Other Details:
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Languages: eng Pagination: 1727-35 Citation Subset: IM |
Copyright Information:
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Copyright © 2010 Elsevier B.V. All rights reserved. |
Affiliation:
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Instituto de Biología y Genética Molecular (IBGM), Departamento de Bioquímica y Biología Molecular y Fisiología, Facultad de Medicina, Universidad de Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), Ramón y Cajal, 7, E-47005 Valladolid, Spain. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Calcium
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metabolism*,
pharmacokinetics* Dose-Response Relationship, Drug Hela Cells Humans Kinetics Mitochondria / drug effects, metabolism* Sodium / pharmacology Temperature |
| Chemical | |
Reg. No./Substance:
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7440-23-5/Sodium; 7440-70-2/Calcium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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