Harrison 2014 Abstract MiP2014

The relationship between cytochrome redox state and oxygen consumption in isolated mouse and beef heart mitochondria during hypoxia.

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MiP2014, Book of Abstracts Open Access

Harrison DK, Fasching M, Fontana-Ayoub M, Gnaiger E (2014)

Event: MiP2014

This study describes a low-noise, rapid spectrophotometric system using visible light (440-605 nm) for the measurement of cytochrome redox state combined with high-resolution respirometry. The system was tested in an investigation using beef and mouse heart isolated mitochondria (BHImt, MHImt) in order to determine the relationship between respiratory rate and cytochrome redox state at steady-state levels of hypoxia. Monophasic hyperbolic relations were observed between respiratory rate, j (OXPHOS with glutamate+malate and saturating ADP concentrations), and oxygen partial pressure, p_O2, in the range <1.1 kPa for both BHImt and MHImt with p_50,j (p_O2 at j=0.5 Jmax) of 0.015 and 0.021 kPa, respectively [1]. The oxidation fractions of cytochromes aa3 and c were biphasic hyperbolic functions of p_O2. The relationships between cytochrome oxidation states and j were more complex with an initial steep decrease in the oxidation fraction of cytochrome c to a value of j of approximately 0.7 followed by a plateaux and a further steep decrease at j<0.2. This relationship was less apparent with cytochrome b redox state. Using these functions, it was possible to create a model that successfully described the measured relationship between cytochrome oxidation state and oxygen consumption.

Labels: MiParea: Respiration 

Stress:Hypoxia  Organism: Rat, Bovines  Tissue;cell: Heart  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.  Enzyme: Complex IV; Cytochrome c Oxidase"Complex IV; Cytochrome c Oxidase" is not in the list (Adenine nucleotide translocase, Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase, Inner mt-membrane transporter, Marker enzyme, Supercomplex, TCA cycle and matrix dehydrogenases, ...) of allowed values for the "Enzyme" property.  Regulation: Cyt c, O2"O2" 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., Redox state  Coupling state: OXPHOS 

HRR: Oxygraph-2k, Spectrophotometry"Spectrophotometry" 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. 

MiP2014 

Affiliation

1-OROBOROS INSTRUMENTS, Innsbruck, Austria; 2-Microvascular Measurements, St Lorenzen, Italy; 3-D Swarowski Research Lab, Dep Visceral Transplant and Thoracic Surgery, Medical Univ Innsbruck, Austria. - [email protected]

References and acknowledgements

Supported in part by K-Regio project MitoCom.

1. Scandurra FM, Gnaiger E (2010) Cell respiration under hypoxia: facts and artefacts in mitochondrial oxygen kinetics. Adv Exp Med Biol 662: 7-25.