Harrison 2015 J Appl Physiol: Difference between revisions
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::::* This publication presents results obtained with a test prototype instrument of the [[O2k-Innovation description|O2k-Innovation]]. | ::::* This publication presents results obtained with a test prototype instrument of the [[O2k-Innovation description|O2k-Innovation]]. | ||
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== MitoFit news 2015#14 == | == MitoFit news 2015#14 == | ||
::::* 2015-09-02: Defining mt-hypoxia at cytochrome redox steady-states, with the [[O2k-Innovation description|O2k-Innovation]]. ยป [[MitoFit news]] | ::::* 2015-09-02: Defining mt-hypoxia at cytochrome redox steady-states, with the [[O2k-Innovation description|O2k-Innovation]]. ยป [[K-Regio_MitoFit#2015 |MitoFit news]] |
Revision as of 16:07, 19 March 2019
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. |
Harrison DK, Fasching M, Fontana-Ayoub M, Gnaiger E (2015) J Appl Physiol
Abstract: 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, JO2, and oxygen partial pressure, pO2, within the range <1.1 kPa (8.3 mmHg; 13 ยตM). p50j (pO2 at 0.5โJmax) was 0.015ยฑ0.0004 and 0.021ยฑ0.003 kPa (0.11 and 0.16 mmHg) for BHImt and MHImt, respectively. Maximum oxygen consumption, Jmax, was measured at saturating ADP levels (OXPHOS capacity) with Complex I-linked substrate supply. Redox states of cytochromes aa3 and c were biphasic hyperbolic functions of pO2. 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 Jmax, pO2 was as low as 0.002 kPa (0.02 ยตM), and trace amounts of oxygen are sufficient to partially oxidize the cytochromes. At higher pO2 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.
โข Bioblast editor: Gnaiger E โข O2k-Network Lab: AT Innsbruck Gnaiger E, AT Innsbruck Oroboros
Labels: MiParea: Respiration, Instruments;methods, Comparative MiP;environmental MiP
Organism: Mouse, Bovines
Tissue;cell: Heart
Preparation: Isolated mitochondria
Regulation: Oxygen kinetics Coupling state: OXPHOS Pathway: N HRR: Oxygraph-2k, TIP2k, O2k-Spectrophotometer
MitoFitPublication
- This publication presents results obtained with a test prototype instrument of the O2k-Innovation.
- ยป More details: O2k-Innovation
MitoFit news 2015#14
- 2015-09-02: Defining mt-hypoxia at cytochrome redox steady-states, with the O2k-Innovation. ยป MitoFit news