After addition of 20 mM calcium ionophore A23187 to cultured PK (pig kidney embryo) cells, [Ca++] in cytosol increased by more than 10 times. The maximum [Ca++] concentration was observed 1-2 min after drug introduction. Later on [Ca++] gradually decreased, and after 30 min of incubation with A23187 [Ca++] its concentration was 3-5 times higher than in the norm, l min after introduction of the calcium ionophore, mitotic spindles shortened for 1/3 and the angle of divergence of spindle microtubules from the centrosome extended. These changes remained for 5 min of treatment. After nocodazole treatment the length of the mitotic spindle reduced (2 min), then mitotic spindle and the metaphase plate were disrupted. The rate of mitotic spindle shortening after addition of the ionophore is about the same as after addition of nocodazole, but after ionophore treatment the metaphase plate remained for more than 5 min. Based on the results obtained we suggest that the maximum distance between spindle poles at metaphase is in the intact cell, and after any perturbation of normal microtubule dynamics the spindle may rapidly collapse. The collapsed mitotic spindle becomes more stable and its size is determined predominantly by kinetochore fibers. The metaphase spindle is completely and rapidly destroyed when the microtubule growth is prohibited, but it is preserved when this growth is restricted.
|Number of pages||3|
|Publication status||Published - Dec 1 1996|
ASJC Scopus subject areas
- Pathology and Forensic Medicine