Myocardial mitochondrial functions in alpha-tocopherol-deficient and -refed rabbits.

In mitochondria from alpha-tocopherol-deficient rabbit hearts (30 days), there was a close correlation between the decline in respiration and the incidence of membrane peroxidation. In the same mitochondria, an increased formation of oxygen radicals was also observed, whereas superoxide dismutase activity was only slightly depressed. The exposure of mitochondria to exogeneous oxygen radicals generated by a xanthine-xanthine oxidase system caused a marked decrease in their oxidative phosphorylation capacity associated with an increase in lipid peroxidation breakdown. This was particularly evident in mitochondria from alpha-tocopherol-deficient rabbits. In mitochondria from deficient animals that had been rehabilitated with alpha-tocopherol, the toxic effect of oxygen radicals was less evident.