Abstract: ObjectiveTo investigate the relationship between cytotoxicity and oxidative stress and arsenic metabolism induced by different kinds of inorganic arsenicals in epidermal keratinocytes cells(HaCaT).MethodsMethyl thiazolyl tetrazolium(MTT) assay was used to evaluate the cell viability.Malondialdehyde(MDA) content and the activity of the superoxide dismutase(SOD) in HaCaT were detected.The intracellular reactive oxygen species(ROS) were detected with flow cytometry and the atomic fluorescence was used to analyze intracellular or extracellular level of different forms of arsenic.ResultsAs₂O₃(200.0 μmol/L)and Na₂HAsO₄·7H₂O(≥50.0 μmol/L)could decrease the cell viability,with the survival rates of 54.8±5.9% and 85.4±9.5%,70.0±4.0% and 58.8±6.0%,and could significantly promote the proliferation of HaCaT cell at low dosage(P<0.01,P<0.05).The MDA levels of iAs^Ⅲ groups increased with dose increasing and iAs^Ⅴgroups showed decrease after an increase with an U-shaped dose-respose curve.The SOD activity showed a dose-effect relation with an U-shaped curve.The intracellular ROS decreased with the order of As₂O₃,Na₂HAsO₄·7H₂O.The extracellular iAs^Ⅲ,iAs^Ⅴcontents were higher than intracellular contents in all groups.The methylation ratio of 5.0 mol/L iAs^Ⅲ group(87.3%) was higher than that of 50.0 mol/L iAs^Ⅲ (61.8%) and the ratio of 5.0 mol/L iAs^Ⅴ groups(40.0%) was higher than that of 250.0 mol/L iAs^Ⅴ(10.5%).The ratio of iAs^Ⅲ groups was higher than that of the iAs^Ⅴ groups.The arsenic levels of the high-dose groups were higher than those of low-dose groups.The efflux ability of low-dose groups were higher and the efflux ability of iAs^Ⅲ groups were lower than those of the iAs^Ⅴ groups.ConclusionThe mechanisms of inorganic arsenic toxicity probably relate to different levels of oxidative stress and arsenical metablism.