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Harrison 2015 J Appl Physiol
Additional label MitoFitPublication  +
Coupling states OXPHOS  +
Has abstract Mitochondrial control of cellular redox st
Mitochondrial control of cellular redox states is a fundamental component of cell signaling in the coordination of core energy metabolism and homeostasis during normoxia and hypoxia. We investigated the relationship between cytochrome redox states and mitochondrial oxygen consumption at steady-state levels of hypoxia in mitochondria isolated from beef and mouse heart (BHImt, MHImt), comparing two species with different cardiac dynamics and local oxygen demands. A low-noise, rapid spectrophotometric system using visible light for the measurement of cytochrome redox states was combined with high-resolution respirometry. Monophasic hyperbolic relations were observed between oxygen consumption, ''J''<sub>O2</sub>, and oxygen partial pressure, ''p''<sub>O2</sub>, within the range <1.1 kPa (8.3 mmHg; 13 µM). ''p''<sub>50''j''</sub> (''p''<sub>O2</sub> at 0.5∙''J''<sub>max</sub>) was 0.015±0.0004 and 0.021±0.003 kPa (0.11 and 0.16 mmHg) for BHImt and MHImt, respectively. Maximum oxygen consumption, ''J''<sub>max</sub>, was measured at saturating ADP levels (OXPHOS capacity) with Complex I-linked substrate supply. Redox states of cytochromes ''aa''<sub>3</sub> and ''c'' were biphasic hyperbolic functions of ''p''<sub>O2</sub>. The relation between cytochrome oxidation state and oxygen consumption revealed a separation of distinct phases from mild to severe and deep hypoxia. When cytochrome ''c'' oxidation increased from fully reduced to 45% oxidised at 0.1 ''J''<sub>max</sub>, ''p''<sub>O2</sub> was as low as 0.002 kPa (0.02 µM), and trace amounts of oxygen are sufficient to partially oxidize the cytochromes. At higher ''p''<sub>O2</sub> under severe hypoxia, respiration increases steeply while redox changes are small. Under mild hypoxia, the steep slope of oxidation of cytochrome ''c'' when flux remains more stable represents a cushioning mechanism maintaining respiration high at the onset of hypoxia.
respiration high at the onset of hypoxia.  +
Has editor [[Gnaiger E]]  +
Has info [ PMID: 26251509 Open Access]  +
Has title Harrison DK, Fasching M, Fontana-Ayoub M, Gnaiger E (2015) Cytochrome redox states and respiratory control in mouse and beef heart mitochondria at steady-state levels of hypoxia. J Appl Physiol 119:1210-8.  +
Instrument and method Oxygraph-2k  + , TIP2k  + , O2k-Spectrophotometer  +
Mammal and model Mouse  + , Bovines  +
MiP area Respiration  + , Instruments;methods  + , Comparative MiP;environmental MiP  +
Pathways N  +
Preparation Isolated mitochondria  +
Respiration and regulation Oxygen kinetics  +
Tissue and cell Heart  +
Was published by MiPNetLab AT Innsbruck Gnaiger E + , AT Innsbruck Oroboros +
Was published in journal J Appl Physiol +
Was published in year 2015  +
Was written by Harrison DK + , Fasching M + , Fontana-Ayoub M + , Gnaiger E +
Categories Publications
Modification date
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14:07:22, 19 March 2019  +
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