Electroneutral efflux of Ca2+ from liver mitochondria.
Respiring liver mitochondria were allowed to export Ca2+ on the endogenous Ca2+/nH+ antiporter in the presence of Ruthenium Red (to inhibit uptake on the Ca2+ uniporter) until a steady state was reached. Addition of sufficient of the ionophore A23187 (which catalyses Ca2+/2H+ exchange) to bring the Ca2+ and H+ gradients into equilibrium did not alter the steady state. Thermodynamic analysis showed that if a Ca2+/nH+ exchange with any value of n other than 2 was at equilibrium, addition of A23187 would have caused an easily measurable change in extramitochondrial free [Ca2+]. Therefore, the endogenous carrier of liver mitochondria catalyses electroneutral Ca2+/2H+ antiport.
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D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D011522:Protons; D051381:Rats; D013816:Thermodynamics
D011522:Protons; D000001:Calcimycin; D002118:Calcium