Figure 3.

Nontoxic doses of selenite decrease glutathione reductase and glutathione in PC-3 cells sensitized with carmustine. (A) PC-3 cells were treated with the indicated concentrations of carmustine (10–40 μM) for 6 hours. Glutathione reductase activity was then measured as described in the Materials and methods section. Each assay was performed in duplicate. The data are presented as the mean ± standard deviation (*P < 0.05; n = 3) and expressed as nanomoles of NADPH oxidized per minute per milligram of protein. Data are normalized to the control. Comparisons shown: (a) significant compared with vehicle-treated control. (B) PC-3 cells were pretreated with 20 μM carmustine for 30 minutes and then treated with the indicated concentrations of selenite (2.5–5 μM) for 6, 12, and 24 hours. Glutathione levels were then determined as described in the Materials and methods section. Data are presented as the mean ± standard deviation (*P < 0.05; n = 3) and expressed as μmoles/mg protein. Data are normalized to the control. Comparisons shown: (a) significant compared with control; (b) significant compared with 2.5 μM selenite-treated cells. (C) PC-3 cells were pretreated with 10 or 20 μM carmustine for 30 minutes and then treated with the indicated concentrations of selenite (2.5–5 μM) for 6 hours. Glutathione reductase activity was determined as described in the Materials and methods section. The data are presented as the mean ± standard deviation (*P < 0.05; n = 3) and expressed as nanomoles of NADPH oxidized per minute per milligram of protein. Data are normalized to the control. Comparisons shown: (a) significant compared with control; (b) significant compared with 2.5 μM selenite-treated cells.

Abbreviations: GSH, glutathione; GR, glutathione reductase.