Fig. 5

Zinc induces intracellular superoxide anion generation in H460 cells. a–i The cells were incubated with specific ROS probes, namely, DHE, DCFH₂-DA, or HPF at 4 °C for 30 min prior to the treatment with zinc (0–50 µM) for 0–3 h and the fluorescence intensity was analyzed by a microplate reader and flow cytometry. Mean intensity was normalized to untreated control cells and represented as relative ROS levels. Values are means of independent triplicate experiments ± SD. *p < 0.05 versus untreated control. j–k The cells were incubated with DHE at 4 °C for 30 min prior to pre-treatment with 50 µM MnTBAP (superoxide anion inhibitor) for 1 h in the presence or absence of zinc (50 µM) for 3 h and the fluorescence intensity was analyzed by a microplate reader and flow cytometry. Mean intensity was normalized to untreated control cells and represented as relative ROS levels. Values are means of independent triplicate experiments ± SD. *p < 0.05 versus untreated control