Differences in sister chromatid exchange (SCE)-induction in vivo by cyclophosphamide in murine strains.

The susceptibility of sister chromatid exchange (SCE)-induction in bone marrow cells by cyclophosphamide (CPA) was tested in DBA/2, AKR, C57BL/6J, C3Hf and BALB/c mice in vivo. Mice were treated with one i.p. injection of 0.4, 2.0 and 10.0 mg/kg body weight of CPA or of saline. The base-line level of SCE was similar in all the strains with about 3 SCE/cell. Increasing concentrations of CPA caused an increased level of SCE. At any dose level, differences in the SCE frequency were observed among the five strains. The greatest difference was seen at the dose of 10 mg/kg, when the DBA/2 strain reached the frequency of 25.5 SCE/cell, whereas 19.3, 12.9, 11.4 and 10.1 SCE/cell were seen respectively in AKR, C57BL/6J, C3Hf and BALB/c mice.