ATLA::Alternatives to Laboratory Animals

Volume 28, Number 3

Cytotoxicity of cadmium, selenium, zinc and copper to mouse myeloma Sp2/0 cells as measured by the MTT assay.

ATLA 28, 473-476, May/June 2000

Inessa Remez,¹ Leonid Rabkin,¹ Hackel Veksler¹ and Maija Baumane²

¹Institute of Occupational and Environmental Health, Medical Academy of Latvia, 16 Dzirciema Street, 1007 Riga, Latvia; ²National Register of Potentially Toxic Chemicals, Centre of Disaster Medicine, 2 Hipokrata Street, 1038 Riga, Latvia

SUMMARY

As part of our general programme to test the toxicity in vitro of heavy metals and, in particular, the interactive cytotoxicity of combinations of these metals, the MTT (tetrazolium) assay was used to test the cytotoxicities of cadmium [Cd(O₂CCH₃)₂], selenium (Na₂SeO₃), zinc (ZnSO₄) and copper (CuSO₄) with an established mouse myeloma cell line (Sp2/0). The influence on the cytotoxicity of cadmium of added subtonic concentrations of the other three metals was also studied. The IC50 values (50% inhibitory concentrations) to the Sp2/0 cells were as follows: Cd-10 µM, Se-1 µM, Zn-10 µM and Cu-100 µM. When selenium, zinc and copper at high, subtonic concentrations (10 nM, 1 µM and 1 µM, respectively) were each combined with clearly toxic concentrations of cadmium (10 µM and 100 µM), the cytotoxicity increase was significant for the cadmium-zinc combination. Previous studies showed that cadmium-zinc combinations at low concentration (5 x 10^-9M) had a synergistic stimulatory effect on cell proliferation in vitro. The present study showed that a toxic concentration of cadmium (0.1 mM) and a sub-toxic concentration of zinc (1 µM) have a synergistic cytotoxic effect in vitro.

Keywords: Combined toxicity, cytotoxicity, heavy metals, mouse myeloma Sp210 cell line, toxicity testing