DISTINCT GENOTOXICITY OF PHENYLMERCURY ACETATE IN HUMAN-LYMPHOCYTES AS COMPARED WITH OTHER MERCURY-COMPOUNDS

In the present study, the frequency of sister chromatid exchanges (SCE s) was assayed to evaluate the genotoxic effects of mercury nitrate (H g2+), methylmercury chloride (CH3HgCl) and phenylmercury acetate (PMA) on human lymphocytes. The free radical scavengers, catalase (CA) and superoxide dismutase (SOD) were tested for their antigenotoxic effects toward PMA. PMA (1-30 mu M) increased SCE frequency in a concentratio n-dependent manner. However, CH3HgCl significantly increased SCE frequ ency only at a concentration of 20 mu M, and all concentrations treate d with Hg2+ did not induce a positive effect. On the other hand, we fi rst reported that 30 mu M Hg2+, 20 mu M CH3HgCl and (3-30 mu M) PMA si gnificantly increased the frequency of endoreduplicated mitosis. PMA w as about 3- or 5-fold more effective in inducing endoreduplication tha n CH3HgCl or Hg2+ at equivalent toxic concentrations, respectively. Ho wever, neither CA nor SOD in concentrations of 75 and 150 mu g/ml show ed antagonistic action on the genotoxic effects of PMA. The results su ggest that the mechanism of PMA-induced genotoxicity is not mediated b y superoxide anion nor H2O2. It is concluded that PMA, which was more effective in inducing the elevation of both SCEs and endoreduplication , may be especially hazardous of the three mercury compounds tested. ( C) 1997 Elsevier Science B.V.