FIG. 1.

Voltage-operated Ca²⁺ channels in P7 human embryonic stem cell-derived neural precursors (hESC NPs). Example of traces (A, C, E) from individual cells for each experimental design show the block of K⁺ responses by specific Ca²⁺ channel antagonists. The cells were first exposed to control K⁺ depolarization and the [Ca²⁺]_i responses were monitored. Note that the amplitude of the control responses to high K⁺ is identical without any run down. Subsequently, the same cell was preincubated for 5 min with Ca²⁺ channel blockers [Cd²⁺/Ni²⁺; Nic: nicardipine and ω-conotoxin MVIIC (MVIIC)] as indicated on the trace and then again challenged with high K⁺. (B) Preincubation of cells with 100 μM Cd²⁺ together with 50 μM Ni²⁺ significantly reduced [Ca²⁺]_i responses in all tested cells (n=7). The trace (C) and bar diagram (D) show the reduction of the high K⁺-induced [Ca²⁺]_i responses by the L-type Ca²⁺ channel blocker 10 μM nicardipine (n=6). The trace (E) shows the K⁺-induced [Ca²⁺]_i responses in the presence of and after preincubation with the P/Q-type Ca²⁺ channel blocker, MVIIC (300 nM). (F) Bar diagram shows the MVIIC inhibition of the high-K⁺ responses (n=5). G, H are confocal images of P7 hESC NPs, co-stained for βIII tubulin (G, H) (middle panel) and for L-type Ca²⁺ CP α1C (H-280) (G), (left panel) or P/Q-type Ca²⁺ CP α1A (H-90) (H), (left panel). Merged images are presented in the right panels (G, H). Scale bars=20 μm. *P=0.05; **P=0.005; ***P=0.0005. Color images available online at www.liebertpub.com/scd