Andrienko 2003 J Exp Biol
Andrienko T, Kuznetsov AV, Kaambre T, Usson Y, Orosco A, Appaix F, Tiivel T, Sikk P, Vendelin M, Margreiter R, Saks VA (2003) Metabolic consequences of functional complexes of mitochondria, myofibrils and sarcoplasmic reticulum in muscle cells. J Exp Biol 206: 2059-2072. |
Andrienko T, Kuznetsov AV, Kaambre T, Usson Y, Orosco A, Appaix F, Tiivel T, Sikk P, Vendelin M, Margreiter R, Saks VA (2003) J. Exp. Biol.
Abstract: Regulation of mitochondrial respiration both by endogenous and exogenous ADP in the cells in situ was studied in isolated and permeabilized cardiomyocytes, permeabilized cardiac fibers and `ghost' fibers (all with a diameter of 10β20 Β΅m) at different (0β3 Β΅moll-1) free Ca2+ concentrations in the medium. In all these preparations, the apparent Km of mitochondrial respiration for exogenous ADP at free Ca2+ concentrations of 0β0.1 Β΅moll-1 was very high, in the range of 250β350 Β΅moll-1, in contrast to isolated mitochondria in vitro (apparent Km for ADP is approximately 20 Β΅moll-1). An increase in the free Ca2+ concentration (up to 3 Β΅moll-1, which is within physiological range), resulted in a very significant decrease of the apparent Km value to 20β30 Β΅moll-1, a decrease of Vmax of respiration in permeabilized intact fibers and a strong contraction of sarcomeres. In ghost cardiac fibers, from which myosin was extracted but mitochondria were intact, neither the high apparent Km for ADP (300β350 Β΅moll-1) nor Vmax of respiration changed in the range of free Ca2+ concentration studied, and no sarcomere contraction was observed. The exogenous-ADP-trapping system (pyruvate kinase + phosphoenolpyruvate) inhibited endogenous-ADP-supported respiration in permeabilized cells by no more than 40%, and this inhibition was reversed by creatine due to activation of mitochondrial creatine kinase. These results are taken to show strong structural associations (functional complexes) among mitochondria, sarcomeres and sarcoplasmic reticulum. Inside these complexes, mitochondrial functional state is controlled by channeling of ADP, mostly via energy- and phosphoryl-transfer networks, and apparently depends on the state of sarcomere structures. β’ Keywords: Mitochondria, Myofibril, Sarcoplasmic reticulum, Cardiomyocyte, Mitochondrial respiration, Muscle, Intracellular energetic unit
β’ O2k-Network Lab: EE Tallinn Saks VA, FR Grenoble Saks VA
Labels:
Organism: Rat
Tissue;cell: Cardiac Muscle"Cardiac Muscle" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property.
Preparation: Isolated Mitochondria"Isolated Mitochondria" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property., Permeabilized Cell or Tissue; Homogenate"Permeabilized Cell or Tissue; Homogenate" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property.
HRR: Oxygraph-2k