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 treatme nt with thiotepa. Male and female Armenian hamsters were similarly sen sitive to the clastogenic action of thiotepa. The lowest effective con centration of thiotepa for Armenian hamsters was 2.5 mg/kg b.w. (6.1% of the LD(50)). The results obtained and analysis of the literature da ta have shown that Armenian hamsters are much more resistant to the cl astogenic action of thiotepa than various other species of rodent. Thi s 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.