Failure of caffeine to influence induced mutation frequencies and the independence of cell killing and mutation induction in V79 Chinese hamster cells.

Using V79 Chinese hamster cells and a replating assay, no effect of caffeine post-treatment on spontaneous or UV- or EMS-induced mutation frequencies to 8-azaguanine resistance was demonstrable. However, considerable potentiation of cell killing was observed. Previous reports that caffeine enhances induced mutation frequencies are explained by an artefact in the situ method used; a similar artefact may also explain the cumulative in situ mutation dose-response curves. Furthermore, the relationship between mutation induction and dose has been shown to be qualitatively distinct from that between cell killing and dose. These differences suggest that cell killing and mutation induction are mediated via independent mechanisms and that pre-mutational lesions may be qualitatively distinct from pre-lethal lesions.