A COMPARATIVE-STUDY OF SYNCHRONIZED AND CONVENTIONAL CULTURE METHODS ON THE MICRONUCLEUS DOSE-RESPONSE CURVE

Micronucleus (MN) dose-response curves have been studied in blood samp les obtained from a healthy volunteer with both a methotrexate synchro nised culture and with a conventional culture method. The curve obtain ed with the synchronised culture, showed better response at higher dos es compared to that obtained with the conventional procedure. Generall y, MN frequency obtained at a dose of 4.0 Gy with the conventional pro cedure is lower, compared to that obtained with dicentric (DC) frequen cy. The present study also showed that MN frequency obtained at this d ose was lower (0.79 +/- 0.09) compared to that obtained with DC freque ncy (0.91 +/- 0.10). However, DC frequency obtained with the synchroni sed culture was almost the same as that obtained with the conventional method, whereas acentric frequency showed an increase with the synchr onised culture. The study showed that the ratios of MN frequency/total aberration frequency observed with the synchronised (0.63) and that o btained with the conventional culture (0.59) was more or less the same indicating that higher acentric frequency may be the cause for higher MN frequency in the synchronised culture. The present study indicates that methotrexate may not be the cause of higher acentric frequency i n synchronised culture. A possible reason for the higher acentric freq uency in the synchronised culture, is highlighted.