FIGURE 4.

Effects of H₂O₂ and catalase on cytosolic redox in CF15 cells. A, Ψ_cyto was measured during short term treatment of roGFP1-expressing cells with 1, 10, and 100 μm H₂O₂ in Ringer's solution. Experiment is typical of 13 similar experiments. B, summary change in Ψ_cyto (compared with controls) as function of [H₂O₂]. Average ± S.D. (n = 13 experiments); ^*, p < 0.05 compared with control. C, Ψ_cyto was measured during 2 h of treatment with 25 or 100 μm H₂O₂. There was a rapid increase during the first 15 min followed by slower decrease toward control levels over the course of about 100 min. D, Ψ_cyto was measured during repeated treatment of cells with 25 μm H₂O₂. Experiment is typical of three similar experiments. E, dose-dependent effects of H₂O₂ on Ψ_cyto were tested in CF15 cells infected with catalase (Ad-Cat, solid line) or β-galactosidase (Ad-lacZ, as control, dotted line) adenovirus. Data are typical of three similar experiments in each case. F, CF15 cells expressing catalase or β-galactosidase were treated with a single dose of 100 μm PYO or with repeated 30-min additions of 100 or 400 μm H₂O₂. Ψ_cyto were recorded before and after 2 h in five different regions of the cover glass each containing ≥10 different roGFP1-expressing cells. Averages ± S.D. (n = 3 experiments) for changes in Ψ_cyto in response to PYO or [H₂O₂] are shown. ^*, p < 0.05 compared with no catalase expression.