Fig. 5. Levels of total glutathione and the lipid peroxidation marker MDA in H₂O₂-treated cells. Cells were pulsed with H₂O₂ (0.5 mM, 20 minutes), and allowed to recover in H₂O₂-free complete medium for up to 24 hours. (A) Evolution of total glutathione during recovery after oxidative challenge. H₂O₂-pulsed cells were harvested by trypsin treatment. An aliquot was saved for solubilization and protein determination. The remaining cell suspension was centrifuged and solubilized in 131 mM 5-sulfosalicylic acid for determination of total, reduced and oxidized glutathione. Results are shown as % values with respect to control cells, harvested with the 5 minutes time point, whose glutathione contents was 29±13 pmol/µg protein, and are the mean±s.d. for at least three independent experiments. (B) Lipid peroxidation in H₂O₂-challenged cells. Cells were treated with 0.5 mM H₂O₂ (20 minutes), and allowed to recover for the times shown before determination of their MDA contents. Results are expressed as % of controls treated in parallel, but without H₂O₂ and are the mean±s.d. for three independent experiments.