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Difference between revisions of "Gnaiger 1995 J Bioenerg Biomembr"

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|journal=J. Bioenerg. Biomembr.
|journal=J. Bioenerg. Biomembr.
|mipnetlab=AT_Innsbruck_GnaigerE
|mipnetlab=AT_Innsbruck_GnaigerE
|abstract=Control and regulation of mitochondrial and cellular respiration by oxygen is discussed with three aims: (1) A review of intracellular oxygen levels and gradients, particularly in heart, emphasizes the dominance of extracellular oxygen gradients. Intracellular oxygen pressure, pO<sub>2</sub>, is low, typically one to two orders of magnitude below incubation conditions used routinely for the study of respiratory control in isolated mitochondria. The pO<sub>2</sub> range of respiratory control by oxygen overlaps with cellular oxygen profiles, indicating the significance of pO<sub>2</sub> in actual metabolic regulation. (2) A methodologically detailed discussion of high-resolution respirometry is necessary for the controversial topic of respiratory control by oxygen, since the risk of methodological artefact is closely connected with far-reaching theoretical implications. Instrumental and analytical errors may mask effects of energetic state and partially explain the divergent views on the regulatory role of intracellular pO<sub>2</sub> . Oxygen pressure for half-maximum respiration, p50, in isolated mitochondria at state 4 was 0.025 kPa (0.2 Torr; 0.3 µM O2), whereas p<sub>50</sub> in endothelial cells was 0.06–0.08 kPa (0.5 Torr). (3) A model derived from the thermodynamics of irreversible processes was developed which quantitatively accounts for near-hyperbolic flux/pO<sub>2</sub> relations in isolated mitochondria. The apparent p<sub>50</sub> is a function of redox potential and protonmotive force. The protonmotive force collapses after uncoupling and consequently causes a decrease in p<sub>50</sub>. Whereas it is becoming accepted that flux control is shared by several enzymes, insufficient attention is paid to the notion of complementary kinetic and thermodynamic flux control mechanisms.
|abstract=Control and regulation of mitochondrial and cellular respiration by oxygen is discussed with three aims: (1) A review of intracellular oxygen levels and gradients, particularly in heart, emphasizes the dominance of extracellular oxygen gradients. Intracellular oxygen pressure, pO<sub>2</sub>, is low, typically one to two orders of magnitude below incubation conditions used routinely for the study of respiratory control in isolated mitochondria. The pO<sub>2</sub> range of respiratory control by oxygen overlaps with cellular oxygen profiles, indicating the significance of pO<sub>2</sub> in actual metabolic regulation. (2) A methodologically detailed discussion of high-resolution respirometry is necessary for the controversial topic of respiratory control by oxygen, since the risk of methodological artefact is closely connected with far-reaching theoretical implications. Instrumental and analytical errors may mask effects of energetic state and partially explain the divergent views on the regulatory role of intracellular pO<sub>2</sub> . Oxygen pressure for half-maximum respiration, p<sub>50</sub>, in isolated mitochondria at state 4 was 0.025 kPa (0.2 Torr; 0.3 µM O2), whereas p<sub>50</sub> in endothelial cells was 0.06–0.08 kPa (0.5 Torr). (3) A model derived from the thermodynamics of irreversible processes was developed which quantitatively accounts for near-hyperbolic flux/pO<sub>2</sub> relations in isolated mitochondria. The apparent p<sub>50</sub> is a function of redox potential and protonmotive force. The protonmotive force collapses after uncoupling and consequently causes a decrease in p<sub>50</sub>. Whereas it is becoming accepted that flux control is shared by several enzymes, insufficient attention is paid to the notion of complementary kinetic and thermodynamic flux control mechanisms.
|keywords=Oxygen limitation, p<sub>50</sub>, Critical oxygen pressure,  Respirometry,  Polarographic oxygen sensor,  Human endothelial cells, Rat liver mitochondria, Intracellular pO2, Oxygen gradients, Kinetics, Nonequilibrium thermodynamics
|keywords=Oxygen limitation, p<sub>50</sub>, Critical oxygen pressure,  Respirometry,  Polarographic oxygen sensor,  Human endothelial cells, Rat liver mitochondria, Intracellular pO2, Oxygen gradients, Kinetics, Nonequilibrium thermodynamics
|info=[http://www.ncbi.nlm.nih.gov/pubmed/8746845 PMID: 8746845]
|info=[http://www.ncbi.nlm.nih.gov/pubmed/8746845 PMID: 8746845]

Revision as of 19:08, 15 September 2010

Publications in the MiPMap
Gnaiger E, Steinlechner-Maran R, Méndez G, Eberl T, Margreiter R (1995) Control of mitochondrial and cellular respiration by oxygen. J. Bioenerg. Biomembr. 27: 583-596.

» PMID: 8746845

Gnaiger E, Steinlechner-Maran R, Mendez G, Eberl T, Margreiter R (1995) J. Bioenerg. Biomembr.

Abstract: Control and regulation of mitochondrial and cellular respiration by oxygen is discussed with three aims: (1) A review of intracellular oxygen levels and gradients, particularly in heart, emphasizes the dominance of extracellular oxygen gradients. Intracellular oxygen pressure, pO2, is low, typically one to two orders of magnitude below incubation conditions used routinely for the study of respiratory control in isolated mitochondria. The pO2 range of respiratory control by oxygen overlaps with cellular oxygen profiles, indicating the significance of pO2 in actual metabolic regulation. (2) A methodologically detailed discussion of high-resolution respirometry is necessary for the controversial topic of respiratory control by oxygen, since the risk of methodological artefact is closely connected with far-reaching theoretical implications. Instrumental and analytical errors may mask effects of energetic state and partially explain the divergent views on the regulatory role of intracellular pO2 . Oxygen pressure for half-maximum respiration, p50, in isolated mitochondria at state 4 was 0.025 kPa (0.2 Torr; 0.3 µM O2), whereas p50 in endothelial cells was 0.06–0.08 kPa (0.5 Torr). (3) A model derived from the thermodynamics of irreversible processes was developed which quantitatively accounts for near-hyperbolic flux/pO2 relations in isolated mitochondria. The apparent p50 is a function of redox potential and protonmotive force. The protonmotive force collapses after uncoupling and consequently causes a decrease in p50. Whereas it is becoming accepted that flux control is shared by several enzymes, insufficient attention is paid to the notion of complementary kinetic and thermodynamic flux control mechanisms. Keywords: Oxygen limitation, p50, Critical oxygen pressure, Respirometry, Polarographic oxygen sensor, Human endothelial cells, Rat liver mitochondria, Intracellular pO2, Oxygen gradients, Kinetics, Nonequilibrium thermodynamics

O2k-Network Lab: AT_Innsbruck_GnaigerE


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Stress:Hypoxia  Organism: Human, Rat  Tissue;cell: Endothelial; Epithelial; Mesothelial Cell"Endothelial; Epithelial; Mesothelial Cell" 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: Intact Cell; Cultured; Primary"Intact Cell; Cultured; Primary" 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., 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. 

Regulation: Respiration; OXPHOS; ETS Capacity"Respiration; OXPHOS; ETS Capacity" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property. 


HRR: Oxygraph-2k, DatLab Software; Separate Application"DatLab Software; Separate Application" is not in the list (Oxygraph-2k, TIP2k, O2k-Fluorometer, pH, NO, TPP, Ca, O2k-Spectrophotometer, O2k-Manual, O2k-Protocol, ...) of allowed values for the "Instrument and method" property., Method"Method" is not in the list (Oxygraph-2k, TIP2k, O2k-Fluorometer, pH, NO, TPP, Ca, O2k-Spectrophotometer, O2k-Manual, O2k-Protocol, ...) of allowed values for the "Instrument and method" property.