Cell Cycle-Dependent Localization of Voltage-Dependent Calcium Channels and the Mitotic Apparatus in a Neuroendocrine Cell Line(AtT-20)
Figure 2
Nifedipine attenuates AtT-20 Cell density. (a) Cell viability. Incubation with the DHP CaV antagonist, nifedipine, results in a dose-dependent decrease in AtT-20 cell number using the colorimetric MTS assay for cell viability. The half maximal dose for this effect is M nifedipine. Graph shows normalized data from 3 experiments. (b) Cell proliferation and mitotic stages. Graph shows mean number of cells for at least 5 fields (≥800 total cells counted for Day 3 for each condition). There is a significant decrease in the total number of cells counted between vehicle control and nifedipine-treated cells (*). There is also a parallel decrease in later phases of mitosis (A/T/C) (*). Nifedipine M; Vehicle = DMSO from which nifedipine is diluted from 10 mM stock solution. (c) Time for transition through mitosis. Measurements for individual AtT-20 cells using time-lapse microscopy. The time from prophase to cytokinesis is depicted for both control (Vehicle) and Nifedipine-treated cells. The mean time for completion of mitosis is indicated by the bold line with the dotted lines representing 2 S.D. from the mean. Nifedipine treated cells show a shift in mean time to complete mitosis as well as an increased number of cells that do not complete mitosis (block) within the 2 S.D. time limit compared to control cells.
