Abstract
Using CHO‐K1, HeLa S3 and two Walker lines (WR and WS) differentially sensitive to cis‐diamminedichloroplatinum(II) (cisplatin), the survival after exposure to cisplatin, mitomycin C, vinblastine, vincristine or cytosine arabinoside has been determined either of clonogens or of cells rendered polyploid by post‐exposure incubation in the presence of cytochalasin B (CB). It is suggested that the inhibition of cytokinesis by CB permits an assessment to be made of the fraction of damage whose expression is cell division‐related, possibly including that resulting from a loss or malsegregation of genetic material. It was found that the response of polykaryons in comparison to clonogens was both agent‐ and cell line‐dependent. After cisplatin exposure, polykaryon survival (defined as the ability to accumulate at least 16C DNA) declined exponentially with dose and was qualitatively, and to some extent quantitatively, similar to that observed previously after irradiation. In HeLa S3, giant cells induced by 10‐20Gy irradiation in the absence of CB exhibited a radiation dose‐dependent reduction in the relative frequency of highly polyploid cells which was similar to that observed in CB‐induced polykaryons.