Mitochondrial calcium release as induced by Hg2+.
Addition of Hg2+ to mitochondria of rat kidney induces efflux of intramitochondrial Ca2+. This reaction is accompanied by a diminution of the NAD(P)H/NAD(P) ratio and a decrease of the internal negative membrane potential. These effects were enhanced by dithiothreitol. The binding of mercuric ions to mitochondria saturates with a maximal binding of 9 nmol min-1 mg-1. The stoichiometry between Ca2+ released and Hg2+ bound showed that in the presence of dithiothreitol, the binding of approximately 1 nmol of Hg2+/mg of protein suffices to induce the release of the accumulated Ca2+. In the electrophoretic analysis of Hg-labeled mitochondrial proteins it was found that 203Hg2+ bound mainly to proteins that have molecular masses of 20 and 30 kDa. It is proposed that Hg2+-induced Ca2+ release is due to modification of--SH groups of these latter proteins.
Chávez
E
E
Departamento de Bioquímica, Instituto Nacional de Cardiología, México, D.F.
Holguín
J A
JA
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003545:Cysteine / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials; D008628:Mercury / Q000378:metabolism / Q000494:pharmacology*; D008634:Mersalyl / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D013367:Submitochondrial Particles / Q000378:metabolism / Q000502:physiology
D008634:Mersalyl; D008628:Mercury; D003545:Cysteine; D002118:Calcium; D004229:Dithiothreitol