Tretter 2012 Free Radic Biol Med

From Bioblast
Publications in the MiPMap
Tretter Laszlo, Adam-Vizi Vera (2012) High Ca2+ load promotes hydrogen peroxide generation via activation of Ξ±-glycerophosphate dehydrogenase in brain mitochondria. Free Radic Biol Med 53:2119-30.

Β» PMID: 23022874

Tretter Laszlo, Adam-Vizi Vera (2012) Free Radic Biol Med

Abstract: H2O2 generation associated with Ξ±-glycerophosphate (Ξ±-GP) oxidation was addressed in guinea pig brain mitochondria challenged with high Ca2+ load (10 ΞΌM). Exposure to 10 ΞΌM Ca2+ induced an abrupt 2.5-fold increase in H2O2 release compared to that measured in the presence of a physiological cytosolic Ca2+ concentration (100 nM) from mitochondria respiring on 5 mM Ξ±-GP in the presence of ADP (2 mM). The Ca2+-induced stimulation of H2O2 generation was reversible and unaltered by the uniporter blocker Ru 360, indicating that it did not require Ca2+ uptake into mitochondria. Enhanced H2O2 generation by Ca2+ was also observed in the absence of ADP when mitochondria exhibited permeability transition pore opening with a decrease in the NAD(P)H level, dissipation of membrane potential, and mitochondrial swelling. Furthermore, mitochondria treated with the pore-forming peptide alamethicin also responded with an elevated H2O2 generation to a challenge with 10 ΞΌM Ca2+. Ca2+-induced promotion of H2O2 formation was further enhanced by the Complex III inhibitor myxothiazol. With 20 mM Ξ±-GP concentration, stimulation of H2O2 formation by Ca2+ was detected only in the presence, not in the absence, of ADP. It is concluded that Ξ±-glycerophosphate dehydrogenase, which is accessible to and could be activated by a rise in the level of cytosolic Ca2+, makes a major contribution to Ca2+-stimulated H2O2 generation. This work highlights a unique high-Ca2+-stimulated reactive oxygen species-forming mechanism in association with oxidation of Ξ±-GP, which is largely independent of the bioenergetic state and can proceed even in damaged, functionally incompetent mitochondria. β€’ Keywords: Mitochondria; Reactive oxygen species; Calcium; Hydrogen peroxide; Ξ±-Glycerophosphate dehydrogenase; Reverse electron transport; Permeability transition pore; Myxothiazol; Ξ±-Glycerophosphate shuttle; Free radicals

β€’ O2k-Network Lab: HU_Budapest_Tretter L

Labels: MiParea: Respiration 

Stress:Oxidative stress;RONS  Organism: Guinea pig  Tissue;cell: Nervous system  Preparation: Isolated mitochondria 

Pathway: Gp  HRR: Oxygraph-2k 

Fura-6F, AmR, Safranin 

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