Enhancement of depolarization-induced synaptosomal calcium uptake and neurotransmitter release by Bay K8644

Ca2+ uptake into submaximally stimulated synaptosomes was augmented by low concentrations of BAY K8644 (0.1-100 nM). Use of either veratrine or potassium as the depolarizing agent produced similar effects. Stimulated release of aspartate, glutamate and GABA was enhanced over a similar concentration range of BAY K8644. The extent of synaptosomal depolarization induced by veratrine was not enhanced by BAY K8644. The results are discussed in relation to BAY K8644 activation of voltage-dependent Ca2+ channels in neural tissue. This is the first report of BAY K8644 acting on synaptosomes at concentrations that correlate to dihydropyridine binding studies.