title: Influence of the beta-hydroxybutyrate/acetoacetate ratio on the redox states of mitochondrial NAD(P) and cytochrome c systems, extramitochondrial ATP/ADP ratio and the respiration of isolated liver mitochondria in the resting state.
abstract: The effect of changes in hydrogen supply on the rate of energy transformation (measured as respiration rate), on the redox state of the NAD(P) and cytochrome c couples and on the extramitochondrial ATP/ADP was investigated with isolated rat liver mitochondria. Hydrogen supply was changed by variation of the beta-hydroxybutyrate/acetoacetate ratio in the incubation medium. In the active state respiration rate was strongly diminished by lowering the beta-hydroxybutyrate/acetoacetate ratio, whereas in the resting state a minor effect was observed. This resulted in a decrease in the respiratory control index (RCI). Even under a metabolic situation of strongly diminished hydrogen supply corresponding to a beta-hydroxybutyrate/acetoacetate ratio equal to 0.5 added ADP was phosphorylated. However, the ATP/ADP ratio generated extramitochondrially amounted to half that obtained at a beta-hydroxybutyrate/acetoacetate ratio of more than 100. Nevertheless at a beta-hydroxybutyrate/acetoacetate ratio of 0.5 the generated extramitochondrial ATP/ADP ratio is near to 100. A comparison of the changes in the available free redox energy with those in the extramitochondrial phosphorylation potential points to a disequilibrium between them in the resting state, too. The experimental results are discussed in the light of the metabolic conditions in vivo.
mesh_terms: D020155:3-Hydroxybutyric Acid; D000090:Acetoacetates / Q000494:pharmacology*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003574:Cytochrome c Group / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects*; D006859:Hydrogen / Q000494:pharmacology; D006885:Hydroxybutyrates / Q000494:pharmacology*; D008930:Mitochondria, Liver / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats
chemical_list: D000090:Acetoacetates; D003574:Cytochrome c Group; D006885:Hydroxybutyrates; D009243:NAD; C016635:acetoacetic acid; D009249:NADP; D000244:Adenosine Diphosphate; D006859:Hydrogen; D000255:Adenosine Triphosphate; D020155:3-Hydroxybutyric Acid