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Regulation of brain mitochondrial H 2 O 2 production by membrane potential and NAD(P)H redox state
Author(s) -
Starkov Anatoly A.,
Fiskum Gary
Publication year - 2003
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2003.01908.x
Subject(s) - nad+ kinase , redox , mitochondrion , respiratory chain , glycerol 3 phosphate dehydrogenase , reactive oxygen species , electron transport chain , chemistry , biochemistry , dehydrogenase , membrane potential , oxidizing agent , depolarization , biology , biophysics , enzyme , inorganic chemistry , organic chemistry
Abstract Mitochondrial production of reactive oxygen species (ROS) at Complex I of the electron transport chain is implicated in the etiology of neural cell death in acute and chronic neurodegenerative disorders. However, little is known regarding the regulation of mitochondrial ROS production by NADH‐linked respiratory substrates under physiologically realistic conditions in the absence of respiratory chain inhibitors. This study used Amplex Red fluorescence measurements of H 2 O 2 to test the hypothesis that ROS production by isolated brain mitochondria is regulated by membrane potential (ΔΨ) and NAD(P)H redox state. ΔΨ was monitored by following the medium concentration of the lipophilic cation tetraphenylphosphonium with a selective electrode. NAD(P)H autofluorescence was used to monitor NAD(P)H redox state. While the rate of H 2 O 2 production was closely related to ΔΨ and the level of NAD(P)H reduction at high values of ΔΨ, 30% of the maximal rate of H 2 O 2 formation was still observed in the presence of uncoupler ( p ‐trifluoromethoxycarbonylcyanide phenylhydrazone) concentrations that provided for maximum depolarization of ΔΨ and oxidation of NAD(P)H. Our findings indicate that ROS production by mitochondria oxidizing physiological NADH‐dependent substrates is regulated by ΔΨ and by the NAD(P)H redox state over ranges consistent with those that exist at different levels of cellular energy demand.