Harrison 2014 Abstract MiP2014
|The relationship between cytochrome redox state and oxygen consumption in isolated mouse and beef heart mitochondria during hypoxia.|
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, pO2, in the range <1.1 kPa for both BHImt and MHImt with p50,j (pO2 at j=0.5 Jmax) of 0.015 and 0.021 kPa, respectively . The oxidation fractions of cytochromes aa3 and c were biphasic hyperbolic functions of pO2. 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
Organism: Rat, Bovines Tissue;cell: Heart Preparation: Isolated mitochondria Enzyme: Complex IV;cytochrome c oxidase Regulation: Cyt c, Oxygen kinetics, Redox state Coupling state: OXPHOS
HRR: Oxygraph-2k, O2k-Spectrophotometer Event: B4, Oral MiP2014
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.
- Scandurra FM, Gnaiger E (2010) Cell respiration under hypoxia: facts and artefacts in mitochondrial oxygen kinetics. Adv Exp Med Biol 662: 7-25.