Diphenyleneiodonium acutely inhibits reactive oxygen species production by mitochondrial complex I during reverse, but not forward electron transport.

TitleDiphenyleneiodonium acutely inhibits reactive oxygen species production by mitochondrial complex I during reverse, but not forward electron transport.
Publication TypeJournal Article
Year of Publication2008
AuthorsLambert, AJ, Buckingham, JA, Boysen, HM, Brand, MD
JournalBiochim Biophys Acta
Volume1777
Issue5
Pagination397-403
Date Published2008 May
ISSN0006-3002
KeywordsAnimals, Electron Transport, Electron Transport Complex I, Female, Hydrogen Peroxide, Membrane Potential, Mitochondrial, Mitochondria, Muscle, Muscle, Skeletal, Onium Compounds, Rats, Rats, Wistar, Reactive Oxygen Species, Superoxides
Abstract

We investigated the effects of diphenyleneiodonium (DPI) on superoxide production by complex I in mitochondria isolated from rat skeletal muscle. Superoxide production was measured indirectly as hydrogen peroxide production. In a conventional medium containing chloride, DPI strongly inhibited superoxide production by complex I driven by reverse electron transport from succinate. In principle, this inhibition could be explained by an observed decrease in the mitochondrial pH gradient caused by the known chloride-hydroxide antiport activity of DPI. In a medium containing gluconate instead of chloride, DPI did not affect the pH gradient. In this gluconate medium, DPI still inhibited superoxide production driven by reverse electron transport, showing that the inhibition of superoxide production was not dependent on changes in the pH gradient. It had no effect on superoxide production during forward electron transport from NAD-linked substrates in the presence of rotenone (to maximise superoxide production from the flavin of complex I) or antimycin (to maximise superoxide production from complex III), suggesting that the effects of DPI were not through inhibition of the flavin. We conclude that DPI has the novel and potentially very useful ability to prevent superoxide production from the site in complex I that is active during reverse electron transport, without affecting superoxide production during forward electron transport.

DOI10.1016/j.bbabio.2008.03.005
Alternate JournalBiochim. Biophys. Acta
Citation Key10.1016/j.bbabio.2008.03.005
PubMed ID18395512
Grant List066750 / / Wellcome Trust / United Kingdom
MC_U105663137 / / Medical Research Council / United Kingdom
066750/B/01/Z / / Wellcome Trust / United Kingdom
/ / Medical Research Council / United Kingdom