INDUCTION OF MICRONUCLEATED ERYTHROCYTES BY MEA, AET, WR-2721 AND X-RAYS

The induction of micronucleated polychromatic erythrocytes (MNPCEs) wa s assessed in the bone marrow of adult male Swiss mice treated with ME A (cysteamine HCl), AET (2-aminoethylisothiouronium Br.HBr), or WR-272 1 (S-2-(3-aminopropylamino)ethyl phosphorothioic acid), at a dose of 2 00 mg/kg body weight, and/or exposed to 6 Gy X-rays. MEA, AET, or WR-2 721 was given alone or 15 min prior to X-ray exposure, and the frequen cy of MNPCEs was determined 24 h after the aminothiol treatment and X- irradiation of mice. A genotoxic effect was shown for MEA, AET, WR-272 1, and X-rays, as well as a protective effect of the aminothiols again st X-ray-induced genotoxicity in the mouse erythropoietic system. The aminothiol drugs given alone, without subsequent X-irradiation, elevat ed the frequency of MNPCEs, and WR-2721 appeared to be less toxic than AET and MEA. After exposure of mice to X-rays, the number of MNPCEs w as distinctly increased. MEA, AET, or WR-2721 administration prior to X-irradiation resulted in a reduction of the X-ray-induced elevation o f the frequency of micronuclei, but a stronger radioprotective effect was obtained following WR-2721 and AET treatment than after MEA applic ation. So, the genotoxic and radioprotective effect of the aminothiols was dependent on the compound applied.