Figure 1.

Effect of melatonin on nickel and BrPA coexposure induced cytotoxicity. Single nickel exposure induced cytotoxicity in BEAS-2B cells was measured with cell viability and LDH release experiments. Cells exposed to different concentrations of NiCl₂ (50-1600 μM) for 24 h (a and b). A glycolysis inhibitor, bromopyruvic acid (BrPA), was applied to coexpose with nickel. At the approach of 18 h post NiCl₂ administration, 1 mM melatonin was added and incubated with cells for an additional 6 h. The effect of melatonin on BrPA and NiCl₂ cotreatment induced cell death was measured with cell viability (c) and LDH release (d). The error bar reflects the S.E.M. of at least three independent experiments. ^∗P < 0.05 compared with the nickel-free control group, and ^#P < 0.05 compared with the same nickel concentration but with the melatonin-free group.