Clastogenic action of thiotepa on bone marrow cells of the Armenian hamster.

Thiotepa (TT) induced chromosomal aberrations in the bone marrow cells of the Armenian hamster, Cricetulus migratorius, in a dose-dependent manner. The maximal clastogenic action was observed 24 h after treatment with thiotepa. Male and female Armenian hamsters were similarly sensitive to the clastogenic action of thiotepa. The lowest effective concentration of thiotepa for Armenian hamsters was 2.5 mg/kg b.w. (6.1% of the LD50). The results obtained and analysis of the literature data have shown that Armenian hamsters are much more resistant to the clastogenic action of thiotepa than various other species of rodent. This resistance is not due to the metabolic activation rates of chemical mutagen in the liver of Armenian hamsters, since thiotepa is a direct-acting clastogen.