Cyclosporin A-Sensitive Cytochrome c Release and Activation of External Pathway of NADH Oxidation in Liver Mitochondria Due to Pore Opening by Acidification of Phosphate-Containing Incubation Medium |
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Authors: | DA Knorre VI Dedukhova M Yu Vyssokikh EN Mokhova |
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Institution: | Department of Bioenergetics, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia. knorre@belozersky.msu.ru |
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Abstract: | Acidification of a high phosphate incubation medium from pH 7.4 to 6.5 promotes increase in rates of succinate oxidation and exogenous NADH oxidation via external (rotenone- and myxothiazol-resistant) pathway by factors 2 and 2.3 respectively. Cyclosporin A prevents these effects. To measure the cytochrome c release, mitochondrial cytochrome c concentration was calculated from absorption spectrum of -band of cytochromes c+c1. The cytochrome c release is shown to be equal to 27±4%, 40±12%, 70±5% at pH 7.4, 7.0, 6.5, respectively, the last value being reduced by cyclosporin A to 10±3%. Immunoblot method gives the similar results. It is concluded that acidification of the high phosphate medium induces release of a large part of the cytochrome c pool from liver mitochondria due to opening the Ca2+-dependent cyclosporin A-sensitive permeability transition pore and subsequent high amplitude swelling. |
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Keywords: | Cytochrome c release acidification permeability transition pore P
i exogenous NADH spectrophotometric method |
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