A CASE OF CAFFEINE-MEDIATED CANCELLATION OF MITOTIC DELAY WITHOUT ENHANCED BREAKAGE IN V79 CELLS

Chinese hamster cells (V79 379A) were grown for 17 h in the presence o f 10 mu g/ml bromodeoxyuridine (BrdU) to obtain cells with potential s ister-chromatid differentiation. At this time batches were irradiated (1.5 Gy, 250 kVp X-rays) and the medium of all flasks replaced with on e containing 10 mu g/ml thymidine with or without 400 mu g/ml caffeine . Metaphases from irradiated and unirradiated batches were sampled eve ry hour for 7 h and FPG stained. All categories of chromatid-type aber rations were scored in G(2) and S phase cells.