Effects of Ni²⁺ Ions on Cell Viability and NO Production of Murine Peritoneal Exudate Cells (Macrophages) with and without Lipopolysaccharide Stimulation

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The purpose of this study was to clarify the cytotoxicity of Ni²⁺ ions against murine peritoneal exudate cells (PEC) (macrophages). First, we examined the cell viability of PEC with and without lipopolysaccharide (LPS) stimulation in culture media containing Ni²⁺ ions up to 1000μmol/L. Results showed that the cytotoxicity of Ni²⁺ ions against PEC was dosedependent and accelerated by LPS stimulation, especially in media with Ni²⁺ ions exceeding 100μmol/L. Second, we measured the production of nitric oxide (NO) from PEC and found that LPS caused the PEC to produce abundant NO. However, high dose of Ni²⁺ ions at concentration more than 200μmol/L hindered and inhibited NO production. These results pointed out that the cytotoxicity of Ni²⁺ ions against macrophages depended on both the Ni²⁺ ion concentration and the presence of bacteria with LPS. Further, NO —a killer of bacteria— was lost when LPS-stimulated macrophages were exposed to high dose of Ni²⁺ ions.