Influence of starvation and clofibrate administration on oxidative phosphorylation by rat liver mitochondria.
Whole cells, homogenates and mitochondrial obtained from the livers of albino rats which were starved for 6 days or more showed a 50% decrease in oxidative activity. The decrease could be corrected by the addition of cytochrome c in vitro. The phosphorylative activity of mitochondria remained unaffected. The decrease in oxidative rate was not observed when starving animals were given the anti-hypercholesterolaemic drug clofibrate. The total cellular concentration of cytochrome c was not affected by starvation. However, the concentration of the pigment in hepatic mitochondria isolated from starving animals was less than half that in normal mitochondria. Clofibrate-treated animals did not show a decreased concentration of cytochrome c in hepatic mitochondria. Mitochondria isolated from starving animals, though deficient in cytochrome c, did not show any decrease in succinate dehydrogenase activity or in the rate of substrate-dependent reduction of potassium ferricyanide or attendant phosphorylation. In coupled mitochondria, ferricyanide may not accept electrons from the cytochrome c in the respiratory chain. Starvation decreases the concentration of high-affinity binding sites for cytochrome c on the mitochondrial membrane. The dissociation constant increases in magnitude.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002994:Clofibrate / Q000494:pharmacology*; D003574:Cytochrome c Group / Q000378:metabolism; D005292:Ferricyanides / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D051381:Rats; D013217:Starvation / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000378:metabolism
D003574:Cytochrome c Group; D005292:Ferricyanides; D013385:Succinate Dehydrogenase; D000251:Adenosine Triphosphatases; D002994:Clofibrate