OXIDATIVE DAMAGE OF MITOCHONDRIA INDUCED BY FE(II)CITRATE OR T-BUTYL HYDROPEROXIDE IN THE PRESENCE OF CA2- EFFECT OF COENZYME-Q REDOX STATE( )

The role of coenzyme Q on the process of mitochondrial membrane damage associated with oxidative stress was studied in a suspension of uncou pled mitochondria exposed to Ca2+ in the presence of Fe(II)citrate or t-butyl hydroperoxide. Reduction of coenzyme Q by succinate was shown to inhibit both inner membrane lipid peroxidation and permeabilization induced by Fe(II)citrate, In contrast, the inner membrane permeabiliz ation induced by Ca2+ alone or Ca2+ plus t-butyl hydroperoxide was pot entiated by the presence of succinate. These results support our previ ous proposition that the mitochondrial damage associated with oxidativ e stress generated by these prooxidants in the presence of Ca2+ is med iated by different mechanisms.