Action of rotenone and related respiratory inhibitors on mammalian cell division. 2 Ultrastructural studies.

Light and electron microscopic examination of cultured mammalian cells treated with the respiratory inhibitor rotenone revealed that chromosome, spindle, and centriole configurations were virtually identical to that of mitotic cells arrested with Colcemid, a microtubule assembly inhibitor. The chromosomes of cells arrested in mitosis with either drug were grouped in a spherical mass near the cell centre and centrioles failed to opposite mitotic poles. Spindle microtubules were observed in limited numbers near some chromosome kinetochores and the centrioles. The outer portions of the cell cytoplasm were devoid of microtubules. Scanning and transmission electron microscopy revealed that cells did not progress beyond early stages of mitosis in the presence of rotenone or Colcemid. The ultrastructure of cells harvested from cultures grown in amytal was similar to that of untreated cells. These observations suggest that rotenone arrests mitosis in mammalian cells by inhibition of spindle microtubule assembly.