Mitochondrial Biosvnthesis Controls the Sensitivitvy of Chinese Hamster Cells to Hydrogen Peroxide

The mechanism of H₂O₂-resistance of Hpr-4, a variant of Chinese hamster V79 cells, was investigated. The effect of H₂O₂ on the mitochondria of the parental and Hpr-4 cells was compared. First, both biochemical and ultrastructural results showed that mitochondria in the parental cells were damaged by exposure to H₂O₂, while those in Hpr-4 cells recovered from the damage. Second, the H₂O₂ resistance of Hpr-4 cells was reversibly reduced or recovered by the addition or removal of inhibitors of mitochondrial biosynthesis, respectively. Third, the parental cells were auxotrophic to pyruvate after exposure to H₂O₂. Fourth, H₂O₂-sensitivity of the parental cells was also enhanced by the inhibition of mitochondrial biosynthesis. From these results, it was concluded that the mitochondria of Hpr-4 cells apparently had a greater resistance to H₂O₂ than those of the parental cells and that functional mitochondria were involved in the recovery of Chinese hamster V79 cells from H₂O₂-induced damage.