Gnaiger 2011 Abstract-MonteVerita: Difference between revisions
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|abstract='''Mitochondrial capacity''': [[OXPHOS]] capacity is evaluated in isolated mitochondria (mt) and permeabilized cells with physiological substrate cocktails to reconstitute tricarboxylic acid cycle function. As a consequence, convergent electron flow from Complexes CI+II of the electron transfer system ([[ | |abstract='''Mitochondrial capacity''': [[OXPHOS]] capacity is evaluated in isolated mitochondria (mt) and permeabilized cells with physiological substrate cocktails to reconstitute tricarboxylic acid cycle function. As a consequence, convergent electron flow from Complexes CI+II of the electron transfer system ([[ET-pathway]]) to the [[Q-junction]] exerts an additive effect on flux [1]. | ||
'''Oxygen kinetics of mt-respiration''': The apparent ''K''<sub>m,O2</sub> or ''c''<sub>50</sub> [ยตM] (''p''<sub>50</sub> [kPa]) of mt-respiration increases linearly with respiratory capacity controlled by metabolic state, from 0.2 to 1.6 ยตM determined by [[high-resolution respirometry]]. O<sub>2</sub> gradients are significant only in large cells including cardiomyocytes. The apparent ''p''<sub>50</sub> increases 100-fold in permeabilized muscle fibers due to diffusion gradients [2]. | '''Oxygen kinetics of mt-respiration''': The apparent ''K''<sub>m,O2</sub> or ''c''<sub>50</sub> [ยตM] (''p''<sub>50</sub> [kPa]) of mt-respiration increases linearly with respiratory capacity controlled by metabolic state, from 0.2 to 1.6 ยตM determined by [[high-resolution respirometry]]. O<sub>2</sub> gradients are significant only in large cells including cardiomyocytes. The apparent ''p''<sub>50</sub> increases 100-fold in permeabilized muscle fibers due to diffusion gradients [2]. |
Revision as of 10:16, 20 October 2017
Gnaiger E (2011) Mitochondrial respiratory capacity at maximum aerobic exercise levels: Are intracellular oxygen levels limiting? Abstract Monte Verita. |
Link: The impact of hypoxia on cells, mice and men
Gnaiger E (2011)
Event: Monte Verita
Mitochondrial capacity: OXPHOS capacity is evaluated in isolated mitochondria (mt) and permeabilized cells with physiological substrate cocktails to reconstitute tricarboxylic acid cycle function. As a consequence, convergent electron flow from Complexes CI+II of the electron transfer system (ET-pathway) to the Q-junction exerts an additive effect on flux [1].
Oxygen kinetics of mt-respiration: The apparent Km,O2 or c50 [ยตM] (p50 [kPa]) of mt-respiration increases linearly with respiratory capacity controlled by metabolic state, from 0.2 to 1.6 ยตM determined by high-resolution respirometry. O2 gradients are significant only in large cells including cardiomyocytes. The apparent p50 increases 100-fold in permeabilized muscle fibers due to diffusion gradients [2].
mt-function at VO2max: Aerobic capacity of the human leg muscle exceeds maximum O2 uptake of isolated mitochondria [3] and v. lateralis during VO2max [4]. Therefore, oxygen supply limits aerobic performance, proportional to the apparent mt-excess capacity [5]. mt-respiration is more sensitive to average pO2 in heterogenous tissues than under homogenous conditions in vitro. Tissue heterogeneity increases the kinetic dependence of flux on average intracellular pO2. High mt-density reinforces the steepness of oxygen gradients and oxygen heterogeneity in the tissue, contributing to the O2 limitation in athletic vs sedentary individuals at VO2max [6]. This provides a functional rationale for the observation that hypoxia does not specifically trigger mt-biogenesis [7].
Contribution to K-Regio MitoCom Tyrol.
[1] Gnaiger 2009; Lemieux et al 2011 Int J Biochem Cell Biol
[2] Gnaiger 2003; Scandurra, Gnaiger 2010 Adv Exp Med Biol.
[3] Rasmussen et al 2001 AJP.
[4] Boushel et al 2011 Mitochondrion.
[6] Richardson et al; Haseler et al JAP.
[7] Pesta et al 2011 AJP; Jacobs et al 2011 JAP.
โข O2k-Network Lab: AT Innsbruck Gnaiger E
Labels: MiParea: Respiration
Organism: Human
Regulation: Oxygen kinetics, Substrate Coupling state: OXPHOS Pathway: N, S, NS HRR: Oxygraph-2k