title: Parallel efflux of Ca2+ and Pi in energized rat liver mitochondria.
abstract: Addition of Ruthenium Red to energized rat liver mitochondria that have previously accumulated Ca2+ and phosphate from the external medium induces a parallel efflux of both these ions. Mersalyl or dithioerythritol, which decrease Ruthenium Red-insensitive Ca2+ efflux, also decrease phosphate efflux to the same extent. Conversely diazenedicarboxylic acid bis(NN-dimethylamide) (DDBA), which increases the Ruthenium Red-induced Ca2+ efflux concurrently increases phosphate release. Dithioerythritol and DDBA, reducing and oxidizing agents of thiol groups respectively, modify Ca2+ and Pi efflux without penetrating the mitochondrial inner membrane. Under all the adopted conditions the membrane potential is preserved. The release of resting respiration and the parallel efflux of Mg2+ and adenine nucleotides, events closely correlated to Ca2+ cycling, are equally prevented either by mersalyl, which inhibits phosphate transport, or dithioerythritol; DDBA has the opposite effect. These findings and the observation that suggest that Ca2+ and phosphate transport in energized liver mitochondria are closely related and dependent on the redox state of membrane-bound thiol groups.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D010101:Oxygen Consumption / Q000187:drug effects; D010710:Phosphates / Q000378:metabolism*; D051381:Rats; D012430:Ruthenium Red / Q000494:pharmacology
chemical_list: D000227:Adenine Nucleotides; D010710:Phosphates; D012430:Ruthenium Red; D008274:Magnesium; D002118:Calcium