Demethylation of Methylmercury in Human Neuroblastoma, Glioblastoma and Liver Cells

Abstract

The demethylation of methylmercury (MeHg) was investigated in human neuroblastoma, glioblastoma and liver cells. In the three cell lines, MeHg uptake reached a plateau within 24hr after MeHg exposure while the cellular inorganic Hg levels increased gradually up to 72hr. Methylviologen, a superoxide anion (O-2) generator, was found to be an effective enhancer of demethylation with only a minor effect on lipid peroxidation in all three cases. Fe(II), a hydroxyl radical (OH·) enhancer, showed little effect on the reaction in the presence of methylviologen, although lipid peroxidation levels were increased significantly. Furthermore, mannitol, an OH· scavenger, had no effect on inorganic Hg production. These results indicate that MeHg can be converted to inorganic Hg and that O-2 might predominantly participate in the demethylation reaction in the cells.