Rapid efflux of Ca2+ from heart mitochondria in the presence of inorganic pyrophosphate |
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| Authors: | A Vercesi A L Lehninger |
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| Institution: | Department of Physiological Chemistry The Johns Hopkins University School of Medicine 725 N. Wolfe Street, Baltimore, MD 21205 USA |
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| 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. |
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| Keywords: | To whom reprint requests should be sent |
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