Stimulation of mitochondrial respiration by physiological concentrations of Ca2+ was studied to determine which components of oxidative phosphorylation are affected by Ca2+. The kinetic dependence of the respiratory chain, phosphorylation subsystem and proton leak on the mitochondrial membrane potential in isolated rat heart mitochondria respiring on 2-oxoglutarate or succinate was measured at two different concentrations of external free Ca2+. The results show that proton leak is not directly affected by Ca2+, but that both the respiratory and phosphorylation systems can be directly stimulated by Ca2+ depending on conditions. Although Ca2+ directly stimulates the phosphorylation system, this has relatively little effect on respiration rate with 2-oxoglutarate in States 3 and 4 because the subsystem has little control over respiration. However, in intermediate states, the phosphorylation system has greater control and Ca2+ stimulation of this system contributes substantially to the stimulation of respiration and phosphorylation. In the case of succinate oxidation neither the respiratory subsystem nor the phosphorylation system is stimulated by Ca2+.
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November 1996
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Research Article|
November 15 1996
Ca2+ stimulates both the respiratory and phosphorylation subsystems in rat heart mitochondria Available to Purchase
Vida MILDAZIENE;
Vida MILDAZIENE
§
*Institute for Biomedical Research, Kaunas Medical Academy, 3007 Kaunas, Lithuania
§To whom correspondence should be addressed.
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Rasa BANIENE;
Rasa BANIENE
*Institute for Biomedical Research, Kaunas Medical Academy, 3007 Kaunas, Lithuania
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Zita NAUCIENE;
Zita NAUCIENE
*Institute for Biomedical Research, Kaunas Medical Academy, 3007 Kaunas, Lithuania
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Ausra MARCINKEVICIUTE;
Ausra MARCINKEVICIUTE
*Institute for Biomedical Research, Kaunas Medical Academy, 3007 Kaunas, Lithuania
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Ramune MORKUNIENE;
Ramune MORKUNIENE
*Institute for Biomedical Research, Kaunas Medical Academy, 3007 Kaunas, Lithuania
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Vilmante BORUTAITE;
Vilmante BORUTAITE
*Institute for Biomedical Research, Kaunas Medical Academy, 3007 Kaunas, Lithuania
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Boris KHOLODENKO;
Boris KHOLODENKO
†A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
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Guy C. BROWN
Guy C. BROWN
‡Department of Biochemistry, University of Cambridge, Cambridge, U.K.
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Publisher: Portland Press Ltd
Received:
July 03 1996
Accepted:
July 24 1996
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 320 (1): 329–334.
Article history
Received:
July 03 1996
Accepted:
July 24 1996
Citation
Vida MILDAZIENE, Rasa BANIENE, Zita NAUCIENE, Ausra MARCINKEVICIUTE, Ramune MORKUNIENE, Vilmante BORUTAITE, Boris KHOLODENKO, Guy C. BROWN; Ca2+ stimulates both the respiratory and phosphorylation subsystems in rat heart mitochondria. Biochem J 15 November 1996; 320 (1): 329–334. doi: https://doi.org/10.1042/bj3200329
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