Negative evidence for an adaptive response to lethal and mutagenic effects of alkylating agents in V79 Chinese hamster cells.

V79 Chinese hamster cells were subjected to a number of different pretreatment regimens with low concentrations of N-methyl-N-nitrosourea (MNU), N-ethyl-N-nitrosourea (ENU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). They were then treated with either MNU or ENU at toxic and mutagenic concentrations. No differences in cell killing or mutation induction to 6-thioguanine resistance were found between pretreated and non-pretreated cells. These results argue against the existence of an adaptive response to alkylating agents in this cell line.