Changes in antioxidative activities induced by Fe (II) and Fe (III) in cultured Vero cells

The toxicity of iron (II) and iron (III) chlorides was studied at different biochemical and cellular levels, including antioxidative and metabolic enzymes and two general indicators of cytotoxicity in Vero monkey kidney cells after 24-h exposure. Iron (II) was fourfold more toxic than Fe (III) in cell proliferation, with EC50 of 5.5 and 22 mM, respectively. Metabolic markers were far more sensitive than cytotoxicity assays at these concentrations. At the highest concentrations of toxicant tested [10 mM Fe(II) and 50 mM Fe(III)], both species produced nearly total inhibition of the relative uptake of neutral red (RNRU) and phosphofructokinase activity (PFK), and stimulated intracellular specific lactate dehydrogenase activity (LDH). Succinate dehydrogenase (SDH) and hexosaminidase (HEX) activities were reduced in dose-dependent manner, as was the antioxidative enzyme glucose-6-phosphate dehydrogenase (G-6-PDH) with both forms of iron. Glutathione reductase (GOR) and glutathione-S-transferase (GST) activities were stimulated by Fe (II) but were inhibited by the higher Fe (III) concentrations. In conclusion, the experimental model may be useful for the study of different metabolic effects induced by the two oxidation states of iron.