Operation of The Mitochondrial Na+/Ca2+ Exchanger Correlates Inversely to Thermodynamic Driving Force
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1
Semmelweis University, Department of Medical Biochemistry, Hungary
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2
Eötvös Loránd University of Sciences, Department of Analytical Chemistry, Hungary
We measured Na+-induced Ca2+ release from Ca2+-loaded rat heart mitochondria respiring on NAD+-linked substrates, for different membrane potential values titrated by graded inhibition of complex I by rotenone. This Na+-induced Ca2+ release was 100% sensitive to CGP-37157, a specific inhibitor of the mitochondrial Na+/Ca2+ exchanger. Ca2+ re-entry was inhibited by Ru360 given after the uptake of 0.02 mM Ca2+. Assuming that the mitochondrial Na+/Ca2+ exchanger carries 3 molecules of Na+ in exchange for a molecule of Ca2+, thereby leading to a net loss of one negative charge, one would expect that the higher the membrane potential (DYm), the lower the amount of Na+ required to induce Ca2+ release. However, we observed that the amount of Na+ inducing Ca2+ release in isolated mitochondria correlated directly with the extent of membrane polarization. We propose that the exchanger may be subject to powerful regulation, resulting in operation inversely related to thermodynamic force.
Keywords:
Neurophysiology,
Neuroscience
Conference:
13th Conference of the Hungarian Neuroscience Society (MITT), Budapest, Hungary, 20 Jan - 22 Jan, 2011.
Presentation Type:
Abstract
Topic:
Neurophysiology
Citation:
Kiss
G,
Konrád
C,
Szabó
Z,
Ádám-Vizi
V and
Chinopoulos
C
(2011). Operation of The Mitochondrial Na+/Ca2+ Exchanger Correlates Inversely to Thermodynamic Driving Force.
Front. Neurosci.
Conference Abstract:
13th Conference of the Hungarian Neuroscience Society (MITT).
doi: 10.3389/conf.fnins.2011.84.00154
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Received:
03 Mar 2011;
Published Online:
23 Mar 2011.
*
Correspondence:
Dr. C. Chinopoulos, Semmelweis University, Department of Medical Biochemistry, Budapest, Hungary, chinopoulos.christos@eok.sote.hu