Neuronal differentiation of Ca2+ channel by nerve growth factor.

The inhibitory effect of nicardipine, a potent Ca2+ channel blocker in muscular cells, on the Ca2+ channel of clonal rat pheochromocytoma cells (PC12h) and cultured rat adrenal medullary cells was studied during the neuronal differentiation mediated by nerve growth factor (NGF). Nicardipine at nM-order concentrations suppressed the high-K+-evoked, Ca2+-dependent release of preloaded [3H]norepinephrine from PC12h cells and adrenal medullary cells, whereas it scarcely inhibited the release from the cultured rat brainstem cells. The inhibitory actions of nicardipine on both PC12h and newborn rat adrenal medullary cells were significantly decreased after these cells were cultured in the presence of NGF. These results suggest that the changes in Ca2+ channel are accompanied by the neuronal differentiation mediated by NGF.