Regulation of respiration controlled by mitochondrial creatine kinase in permeabilized cardiac cells in situ. Importance of system level properties.
The main focus of this investigation is steady state kinetics of regulation of mitochondrial respiration in permeabilized cardiomyocytes in situ. Complete kinetic analysis of the regulation of respiration by mitochondrial creatine kinase was performed in the presence of pyruvate kinase and phosphoenolpyruvate to simulate interaction of mitochondria with glycolytic enzymes. Such a system analysis revealed striking differences in kinetic behaviour of the MtCK-activated mitochondrial respiration in situ and in vitro. Apparent dissociation constants of MgATP from its binary and ternary complexes with MtCK, Kia and Ka (1.94+/-0.86 mM and 2.04+/-0.14 mM, correspondingly) were increased by several orders of magnitude in situ in comparison with same constants in vitro (0.44+/-0.08 mM and 0.016+/-0.01 mM, respectively). Apparent dissociation constants of creatine, Kib and Kb (2.12+/-0.21 mM 2.17+/-0.40 Mm, correspondingly) were significantly decreased in situ in comparison with in vitro mitochondria (28+/-7 mM and 5+/-1.2 mM, respectively). Dissociation constant for phosphocreatine was not changed. These data may indicate selective restriction of metabolites' diffusion at the level of mitochondrial outer membrane. It is concluded that mechanisms of the regulation of respiration and energy fluxes in vivo are system level properties which depend on intracellular interactions of mitochondria with cytoskeleton, intracellular MgATPases and cytoplasmic glycolytic system.
Guzun
Rita
R
Laboratory of Fundamental and Applied Bioenergetics, INSERM U884, Joseph Fourier University, Grenoble, France.
Timohhina
Natalja
N
Tepp
Kersti
K
Monge
Claire
C
Kaambre
Tuuli
T
Sikk
Peeter
P
Kuznetsov
Andrey V
AV
Pison
Christophe
C
Saks
Valdur
V
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D019069:Cell Respiration / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D003401:Creatine / Q000494:pharmacology; D052281:Creatine Kinase, Mitochondrial Form / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D010725:Phosphocreatine / Q000494:pharmacology; D010728:Phosphoenolpyruvate / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D002316:Cardiotonic Agents; D010725:Phosphocreatine; D010728:Phosphoenolpyruvate; D000255:Adenosine Triphosphate; D011770:Pyruvate Kinase; D052281:Creatine Kinase, Mitochondrial Form; D003401:Creatine