Toosendanin increases free-Ca2+ concentration in NG108-15 cells via L-type Ca2+ channels

AIM: To examine if toosendanin (TSN) affects intracellular free-Ca2+ concentration ([Ca2+](i)) in neuroblastomaxglioma hybrid cells (NG108-15 cells). METHODS: The [Ca2+](i) was determined by laser-scanning confocal microscopic imaging technique in which Fluo-3 was used as Ca2+ indicator. RESULTS: TSN induced an increase in resting [Ca2+](i) and in high K+-evoked Ca2+ transient in differentiated NG108-15 cells. The TSN-induced increase in [Ca2+](i) was dose-dependent and disappeared in CdCl2-, nifedipine-containing or Ca2+-free solution, and appeared after washing out the Ca2+ channel blockers or adding Ca2+. CONCLUSION: TSN increased [Ca2+](i) in differentiated NG108-15 cells. The [Ca2+](i) enhancement was due to the influx of extracellular Ca2+ and related to L-type Ca2+ channels.