title: Rapid efflux of Ca2+ from heart mitochondria in the presence of inorganic pyrophosphate.
abstract: Inorganic pyrophosphate (PPi) in the intracellular concentration range causes rapid efflux of Ca2+ from rat heart mitochondria oxidizing pyruvate + malate in a low Na+ medium. Half-maximal rates of Ca2+ efflux were given by 20 microM PPi. During and after PPi-stimulated Ca2+ efflux the mitochondria retain their structural integrity and complete respiratory control. Carboxyatractyloside inhibits PPi-stimulated Ca2+ efflux, indicating PPi must enter the matrix in order to promote Ca2+ efflux. Heart mitochondria have a much higher affinity for PPi uptake and PPi-induced Ca2+ efflux than liver mitochondria.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D011756:Diphosphates / Q000494:pharmacology*; D007700:Kinetics; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D012430:Ruthenium Red / Q000494:pharmacology
chemical_list: D011756:Diphosphates; D012430:Ruthenium Red; D002118:Calcium