Toxicity and chromosomal damage in fetal Syrian hamster and human pulmonary epithelial cells

In order to test the hypothesis that human chromosomes are more stable than those of rodents, we compared the fetal human and Syrian hamster pulmonary epithelial cell lines for their sensitivity to the induction of cytotoxicity (CT), chromosomal aberrations (CAs) and sister-chromatid exchanges (SCEs). One day after plating, the cells were exposed for 2 h to various doses of ENU dissolved in an exposure medium consisting of McIlvaine buffer, RPMI 1640, and bovine serum albumin. CAs and SCEs were examined in 24-64 post-exposure hours by the standard methods, while CT was determined by cell counts. The frequency of CAs (particularly chromatid exchanges) and that of SCEs showed clear dose dependency and was remarkably higher in the hamster than in the human cells. CT determined in 1 week of post-exposure incubation showed a similar dose response for both cell lines with sharply declining regressions. These results suggest that human chromosomes are indeed more resistant to ENU-inducible aberrations than hamster chromosomes and that CT may not always be directly associated with chromosomal damage.