Nimodipine and flunarizine have different effects on survival and morphology of PC12 cells during nerve growth factor deprivation.

The purpose of this study was to examine the effect of antagonists of different subtypes of Ca(2+) channels (nimodipine and flunarizine) and two types of Ca(2+) chelating agents (the cell permeant Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid acetoxymethylester (BAPTA-AM) and the cell non-permeant Ca(2+) chelator EGTA) on neurite retraction and cell death of nerve growth factor (NGF)-differentiated PC12 cells after NGF deprivation. We demonstrated that flunarizine and nimodipine, but not BAPTA-AM and EGTA, provided protection against cell death due to NGF deprivation. Using time-lapse videomicroscopy and quantitative image analysis, we found that retraction of neurites was an early and fast phenomenon after removal of NGF. None of the compounds tested (flunarizine, nimodipine, BAPTA-AM, EGTA) could prevent the retraction of neurites.