title: Differential effects of pre- and posttreatment of sodium arsenite on the genotoxicity of methyl methanesulfonate in Chinese hamster ovary cells.
abstract: Pretreatment of sodium arsenite reduces hypoxanthine-guanine phosphoribosyltransferase mutagenicity and overcomes the inhibition of mitosis and cell proliferation but has no apparent effect on the cytotoxicity and clastogenicity in methyl methanesulfonate (MMS)-treated Chinese hamster ovary cells. Posttreatment of sodium arsenite drastically increases the cytotoxicity, clastogenicity, hypoxanthine-guanine phosphoribosyltransferase mutagenicity, and inhibition of mitosis and cell proliferation induced by MMS. Sodium arsenite either pre- or posttreatment has no apparent effect on the MMS-induced sister chromatid exchanges. The present results indicate that pretreatment of sodium arsenite not only does no harm but may even benefit the MMS-treated cells. On the contrary, posttreatment of sodium arsenite is cogenotoxic.
mesh_terms: D000818:Animals; D001151:Arsenic / Q000633:toxicity*; D018053:Arsenites; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D006224:Cricetinae; D003412:Cricetulus; D004357:Drug Synergism; D005260:Female; D008741:Methyl Methanesulfonate / Q000633:toxicity*; D009153:Mutagens; D009154:Mutation; D010053:Ovary; D012854:Sister Chromatid Exchange / Q000187:drug effects; D017670:Sodium Compounds
chemical_list: D018053:Arsenites; D009153:Mutagens; D017670:Sodium Compounds; C017947:sodium arsenite; D008741:Methyl Methanesulfonate; D001151:Arsenic