title: The participation of NADP, the transmembrane potential and the energy-linked NAD(P) transhydrogenase in the process of Ca2+ efflux from rat liver mitochondria.
abstract: The pyridine nucleotide specificity, the participation of delta psi, and the energy-linked transhydrogenase in the process of Ca2+ efflux stimulated by the oxidized state of NAD(P) were examined in rat liver mitochondria energized by ascorbate + TMPD. The following observations were made: The Ca2+ efflux rate is independent of the redox state of mitochondrial NAD, but is at a minimum when mitochondrial NADP is in the reduced state and accelerated several-fold when it is in the oxidized state. When the redox state of NADP is shifted to a more oxidized state, the steady-state level of Ca2+ in the medium increased and delta psi decreased in proportion to the mitochondrial NADP+ level. The activity of the energy-linked NAD(P) transhydrogenase seems to be a key element in determining the redox state of NADP and thus of Ca2+ retention and efflux from mitochondria.
mesh_terms: D000090:Acetoacetates / Q000494:pharmacology; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004579:Electron Transport; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D009250:NADP Transhydrogenases / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains; D013050:Spectrometry, Fluorescence; D013772:Tetramethylphenylenediamine / Q000494:pharmacology
chemical_list: D000090:Acetoacetates; C016635:acetoacetic acid; D009249:NADP; D009250:NADP Transhydrogenases; D013772:Tetramethylphenylenediamine; D001205:Ascorbic Acid; D002118:Calcium