EFFECT OF BETA-CAROTENE ON CLASTOGENIC EFFECTS OF MITOMYCIN-C, METHYLMETHANESULFONATE AND BLEOMYCIN IN CHINESE-HAMSTER OVARY CELLS

The effect of beta-carotene on the frequencies of micronuclei (MN) ind uced in cytochalasin blocked binucleated Chinese hamster ovary cells ( CHO) by a bifunctional alkylating agent mitomycin C (MMC), a monofunct ional alkylating agent methyl methanesulphonate (MMS) and a radio-mime tic agent bleomycin (BLEO) was investigated. Four different modes of a pplication of the combination of clastogens and beta-carotene were exa mined (pre-treatment, simultaneous treatment, pre- + simultaneous trea tment and post-treatment). The results obtained showed no effect of be ta-carotene on the frequencies of MN induced by MMS, a slight but not statistically significant reduction of MMC-induced MN only when beta-c arotene was used in low concentrations (0.25 and 0.5 mu M) and a poten tiation of the clastogenicity of bleomycin by beta-carotene in three o f the treatment regimes utilized, post-treatment being ineffective. On the basis of these results it can be concluded that the effect of bet a-carotene on clastogenesis induced by chemicals depends on the type a nd mechanism of action of the clastogen used as well as the treatment protocol employed.