Mutation, DNA labeling, and transformation of BHK-21/CL 13 cells by MNNG, and nitrosocimetidine.

N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) has been reported to induce BHK-21/Cl 13 cell growth in agar suspension. To determine if MNNG was also mutagenic to BHK cells, an ouabain-resistance mutation assay was established using these cells. In this system MNNG was compared to nitrosocimetidine (NC). MNNG and NC did induce ouabain-resistant mutations in BHK cells. The ability of the test compounds to methylate DNA in BHK cells was also determined, and both MNNG and NC yielded detectable levels of 7-methylguanine in treated cells. MNNG and NC were tested for the ability to transform BHK cells, and did. NC was found to be as effective a mutagen and transforming agent in BHK cells as MNNG when administered at equitoxic concentrations; approx. 4-fold less effective at equimolar concentrations.