Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/78262
Type: Artigo de periódico
Title: CA2+-INDUCED MITOCHONDRIAL-MEMBRANE PERMEABILIZATION - ROLE OF COENZYME-Q REDOX STATE
Author: KOWALTOWSKI, AJ
CASTILHO, RF
VERCESI, AE
Abstract: Rotenone-poisoned rat liver mitochondria energized by succinate addition, after a 5-min period of preincubation in presence of 10 mu M 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(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, ruthenium red, catalase, or dithiothreitol, just before succinate or O-2 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.
Subject: MITOCHONDRIAL OXIDATIVE DAMAGE
REACTIVE OXYGEN SPECIES
PROTEIN OXIDATION
Editor: Amer Physiological Soc
Rights: embargo
Date Issue: 1995
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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