Rifampicin-induced chromatid exchanges in Sarcoma-180 mouse ascites cells

Sarcoma-180 ascites tumour-bearing male mice were injected i.p. with single dose of 0.5, 2.5, 5 mg/kg body wt. of rifampicin. Cells were sampled for mitotic chromosome analysis 4, 16 or 24 h after treatment. The maximal yield of chromatid-type aberrations induced was found 24 h after treatment with 5 mg/kg of rifampicin. More than 60% of the cells carried at least one chromatid exchange. The majority of these were exchanges derived from breaks in the centromeric heterochromatin.