Stable and inducible arsenite resistance in Chinese hamster cells.

A number of Chinese hamster V79 cell sublines that are arsenite resistant or arsenite sensitive were isolated. After more than 6 months of growth in the absence of arsenite, these sublines still maintain their arsenite-resistant or -sensitive phenotypes. At least some arsenite-resistant cell lines are also cross-resistant to sodium arsenate and potassium antimonyl tartrate. Wild-type or arsenite-resistant sublines show a further increase in resistance to toxic concentrations of arsenite after pretreatment with a nontoxic concentration. Pretreatment of cells with a nontoxic dose of arsenite also increased their survival to toxic doses of antimonite. Likewise, pretreatment with antimonite increased survival to arsenite as well as to antimonite. The inducible arsenite resistance increases with pretreatment time, reaching a plateau after 8 hr of pretreatment. Fusion of arsenite-resistant cells with arsenite-sensitive cells demonstrated a clear dominance of arsenite resistance. These results suggest that mammalian cells contain an arsenite/antimonite pump whose activity may be modulated by prior exposure to arsenite or antimonite.