SCE induction in Chinese hamster ovary cells (CHO) exposed to G agents

Cultured Chinese hamster ovary (CHO) cells were exposed to two neurotoxic organophosphates, either sarin (GBI, GBII) at 1.4 X 10(-3) M or soman (GD) at 1.1 and 2.2 X 10(-3) M for 1 h, grown and their metaphase chromosomes scored for sister-chromatid exchanges (SCE). No cytotoxicity was seen with either agent at any dose level tested. Since histograms of SCE per cell showed that they were non-symmetrically arrayed around the mean, the number of SCEs were analyzed by using the nonparametric tests, Mann-Whitney and Kruskall-Wallis. Agents GBI and GBII did not show any significant increase in SCE over baseline. On the other hand, GD demonstrated a statistically significant increase in SCE with and without metabolic activation. Ethyl methanesulfonate (EMS) alone at 5 X 10(-3) M and cyclophosphamide (CP) at 10(-4) M in the presence of rat microsomes (S9) induced a 3- and 8-fold increase in SCE per cell, respectively.