Tretter 2012 Free Radic Biol Med

Tretter L, Adam-Vizi V (2012) High Ca2+ load promotes hydrogen peroxide generation via activation of α-glycerophosphate dehydrogenase in brain mitochondria. Free Radic Biol Med 53:2119-30.

» PMID: 23022874

Tretter L, Adam-Vizi V (2012) Free Radic Biol Med

Abstract: H₂O₂ generation associated with α-glycerophosphate (α-GP) oxidation was addressed in guinea pig brain mitochondria challenged with high Ca²⁺ load (10 μM). Exposure to 10 μM 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 α-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 μM Ca²⁺. Ca²⁺-induced promotion of H₂O₂ formation was further enhanced by the Complex III inhibitor myxothiazol. With 20 mM α-GP concentration, stimulation of H₂O₂ formation by Ca²⁺ was detected only in the presence, not in the absence, of ADP. It is concluded that α-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 α-GP, which is largely independent of the bioenergetic state and can proceed even in damaged, functionally incompetent mitochondria. • Keywords: Mitochondria; Reactive oxygen species; Calcium; Hydrogen peroxide; α-Glycerophosphate dehydrogenase; Reverse electron transport; Permeability transition pore; Myxothiazol; α-Glycerophosphate shuttle; Free radicals

• O2k-Network Lab: HU_Budapest_Tretter L

Labels: MiParea: Respiration 

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

HRR: Oxygraph-2k 

Fura-6F; Amplex Red; Safranin