ABSTRACT
The regulatory role of adenine nucleotide translocase in oxidative phosphorylation was determined by titration of respiration of isolated rabbit heart mitochondria with carboxyatractyloside in the creatine phosphokinase ADP-regenerating system, which is not rate-limiting. It was found that the respiration rate is not controlled by adenine nucleotide translocase in states 3 and 4. Within the physiological region of respiration (30-70% of the maximal rate), the control coefficient for ADP/ATP translocase is 0.62-0.75. Thus, translocase plays a key role in the regulation of oxidative phosphorylation.
Subject(s)
Mitochondria, Heart/metabolism , Mitochondrial ADP, ATP Translocases/metabolism , Nucleotidyltransferases/metabolism , Oxidative Phosphorylation , Animals , Kinetics , Mitochondria, Heart/enzymology , Oxidation-Reduction , Phosphocreatine/metabolism , Rabbits , Succinates/metabolismABSTRACT
A regulatory role of adenine nucleotide translocator (ANT) was determined by titration of mitochondrial respiration (state 3) with carboxyatractyloside. It was shown that ANT regulates pyruvate oxidation: the control strength is more pronounced after depletion of endogenous substrates or after the increase in extramitochondrial ATP/ADP. The rate of succinate oxidation is controlled mainly by succinate dehydrogenase, while ANT does not participate in its regulation.
Subject(s)
Adenine Nucleotides/metabolism , Mitochondria, Heart/metabolism , Pyruvates/metabolism , Adenosine Diphosphate/metabolism , Adenosine Triphosphate/metabolism , Animals , Atractyloside/analogs & derivatives , Atractyloside/analysis , Oxidative Phosphorylation , Rabbits , Succinate Dehydrogenase/metabolismABSTRACT
Myocardial mitochondria (MCh), isolated with rotenone (MCh + RO) and in absence of rotenone (MCh - RO), were studied in rabbits with ischemia (0.5 hr autolysis) and in controls. Content of acyl-CoA was increased by 50%, linoleic acid - by 49% and lysophosphatidyl choline - by 37% in MCh + RO of control animals as compared with the MCh - RO preparation. In the MCh + RO preparation from rabbits with ischemia content of acyl-CoA was increased by 62%, while concentration of free fatty acids (FFA) and phospholipids was similar to those of the MCh - RO preparation. After isolation of mitochondria with rotenone composition of adenine nucleotides was distinctly altered. Content of ATP was decreased by 27% in mitochondria of both ischemic and control animals, although total amount of adenine nucleotides was decreased only slightly. As shown by estimation of succinate oxidation and membrane potential rotenone did not affect the mitochondrial respiration. In mitochondria of ischemic rabbits concentrations of FFA and lysophosphatidyl choline were increased, whereas content of ATP, total amount of adenine nucleotides, the rate of succinate oxidation and membrane potential were decreased. The method developed, isolation of mitochondria with rotenone, may be used in studies of the role of acyl-CoA in energy metabolism of cells.
