Effects of potassium dichromate on mitosis of cultured mammalian cells

We have analyzed the effects of a soluble Cr61 compound (potassium dichromate) in a human cell line (HEp), taking into account: A) the changes of mitotic index; b) the changes of the frequency of the different mitotic phases; c) the induction rates of the main caryological and cytological alterations. Our experiments indicate that dichromate induces: 1) a blockage of the cells which are in mitosis at the time of treatment, which takes place at metaphase and anaphase; 2) an early mitotic inhibition on the cells which are in the G2 phase of the cell cycle; 3) a recovery of cell division, after the mitotic inhibition, apparently accompanied by a partial cell synchronization; 4) a late mitotic blockage when cell division recovers, which occurs mainly at metaphase. Such blockage is related to several caryological and cytological alterations; sticky or lagging unoriented chromosomes in the metaphase plate, chromosome bridges at anaphase and telophase, cytoplasmic bridges at interphase; 5) a large proportion of multinucleated (mostly binucleated) cells, whose rate follows telophase onset. On account of the high frequency of chromosome and cytoplasmic bridges, it is suggested that binucleated cells derive from fusion of sister, post-mitotic cells. The above results show that Cr61 can induce marked cytotoxic and cytogenic effects, related to a differential action on the different phases of the cell cycle. © 1977, Taylor & Francis Group, LLC.