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Gnaiger 2011 Abstract-MonteVerita

From Bioblast
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 (ETS) to the Q-junction exerts an additive effect on flux [1].

Oxygen kinetics of mt-respiration: The apparent Km,O2 or c50 [Β΅M] (p50 [kPa]) of mt-respiration increases linearly with respiratory capacity controlled by metabolic state, from 0.2 to 1.6 Β΅M 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

[5] Gnaiger et al 1998 JEB

[6] Richardson et al; Haseler et al JAP

[7] Pesta et al 2011 AJP; Jacobs et al 2011 JAP


β€’ O2k-Network Lab: AT Innsbruck Gnaiger E


Labels:

Stress:Hypoxia  Organism: Human  Tissue;cell: Skeletal Muscle"Skeletal Muscle" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property. 



HRR: Oxygraph-2k