Direct measurement of energy fluxes from mitochondria into cytoplasm in permeabilized cardiac cells in situ: some evidence for Mitochondrial Interactosome.
The aim of this study was to measure energy fluxes from mitochondria in isolated permeabilized cardiomyocytes. Respiration of permeabilized cardiomyocytes and mitochondrial membrane potential were measured in presence of MgATP, pyruvate kinase - phosphoenolpyruvate and creatine. ATP and phosphocreatine concentrations in medium surrounding cardiomyocytes were determined. While ATP concentration did not change in time, mitochondria effectively produced phosphocreatine (PCr) with PCr/O(2) ratio equal to 5.68 +/- 0.14. Addition of heterodimeric tubulin to isolated mitochondria was found to increase apparent Km for exogenous ADP from 11 +/- 2 microM to 330 +/- 47 microM, but creatine again decreased it to 23 +/- 6 microM. These results show directly that under physiological conditions the major energy carrier from mitochondria into cytoplasm is PCr, produced by mitochondrial creatine kinase (MtCK), which functional coupling to adenine nucleotide translocase is enhanced by selective limitation of permeability of mitochondrial outer membrane within supercomplex ATP Synthasome-MtCK-VDAC-tubulin, Mitochondrial Interactosome.
Timohhina
Natalia
N
Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
Guzun
Rita
R
Tepp
Kersti
K
Monge
Claire
C
Varikmaa
Minna
M
Vija
Heiki
H
Sikk
Peeter
P
Kaambre
Tuuli
T
Sackett
Dan
D
Saks
Valdur
V
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D019069:Cell Respiration / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D052281:Creatine Kinase, Mitochondrial Form / Q000378:metabolism; D003404:Creatinine / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D053078:Membrane Potential, Mitochondrial / Q000502:physiology*; D008929:Mitochondria, Heart / Q000502:physiology*; D008954:Models, Biological; D010101:Oxygen Consumption / Q000502:physiology; D010725:Phosphocreatine / Q000096:biosynthesis; D010728:Phosphoenolpyruvate / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism; D051381:Rats; D014404:Tubulin / Q000378:metabolism
D014404:Tubulin; D010725:Phosphocreatine; D010728:Phosphoenolpyruvate; D000255:Adenosine Triphosphate; D003404:Creatinine; D011770:Pyruvate Kinase; D052281:Creatine Kinase, Mitochondrial Form