Dihydropyridines as potent calcium channel blockers in neuronal cells.

Nicardipine, one of the dihydropyridine derivatives, in a nanomolar concentration range suppressed the high K+ -induced neurotransmitter release from cultured neuronal cells (chick embryonic neural retina cells and clonal rat pheochromocytoma cells). The high K+ -induced Ca2+ uptake into pheochromocytoma cell was also blocked by nicardipine in the same concentration range. [3H]Nitrendipine, another dihydropyridine derivative, bound specifically to pheochromocytoma cell homogenate in a saturable manner. We concluded that dihydropyridines block and bind to the high K+ -sensitive Ca2+ channels in neuronal cells.