Fig. 7. Effects of sodium hydrosulphide (NaHS, an H₂S donor) on the generation of intracellular reactive oxygen species (ROS) and levels of lipid peroxidation (MDA) in normal rat kidney proximal cells (NRK-52^E) contaminated by uranium. The kidney cells were pretreated with different concentrations of NaHS (50, 100 or 200 μM) for 30 min and then intoxicated with uranyl acetate (400 μM) for 24 h. Intracellular ROS (A) were then determined by fluorescent analysis using a 2,7- dichlorofluorescein diacetate (DCF-DA) probe, and MDA content (B) was measured by the standard commercial kit as described in the “Materials and methods” section. Values are expressed as the mean ± SE (n = 5). An asterisk represents a significant difference between cells treated with uranium alone and untreated cells; a sharp sign represents a significant difference between cells treated with uranium alone and uranium pulsing NaHS treated cells (two-way ANOVA, **P < 0.01, ^#P < 0.05, ^##P < 0.01).