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Type: Artigo de periódico
Title: Ca2+-induced Mitochondrial Membrane Permeabilization: Role Of Coenzyme Q Redox State
Author: Kowaltowski A.J.
Castilho R.F.
Vercesi A.E.
Abstract: Rotenone-poisoned rat liver mitochondria energized by succinate addition, after a 5-min period of preincubation in presence of 10 μM Ca2+, produce H2O2 at much faster rates, undergo extensive swelling, and are not able to retain the membrane potential and accumulated Ca2+. Similar results were obtained when a suspension of rat liver mitochondria preincubated in anaerobic medium for 5 min was reoxygenated. The addition of either ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid, ruthenium red, catalase, or dithiothreitol, just before succinate or O2 addition, prevented mitochondrial swelling, indicating the involvement of Ca2+, reactive oxygen species, and oxidation of membrane protein thiols in this process of membrane permeabilization. Inhibition of mitochondrial swelling by cyclosporin A suggests that the membrane alterations observed under these experimental conditions are related to opening of the permeability transition pore. The presence of carbonyl cyanide p-trifluoromethoxyphenylhydrazone, which prevents Ca2+ cycling across the membrane, did not inhibit mitochondrial swelling when Ca2+ influx into the mitochondrial matrix was driven by a high Ca2+ gradient. When rotenone plus antimycin A-poisoned mitochondria were energized by N,N,N',N'-tetramethyl-p-phenylenediamine, which reduces respiratory chain complex IV, mitochondrial swelling did not occur, unless succinate, which reduces coenzyme Q, was also added. It is concluded that reduced coenzyme Q is the electron source for oxygen radical production during Ca2+-stimulated oxidative damage of mitochondria.
Rights: fechado
Identifier DOI: 
Date Issue: 1995
Appears in Collections:Unicamp - Artigos e Outros Documentos

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