Figure 6.

Calcineurin effects are downstream of L-type VGCCs. A, Calcineurin activity does not affect KCl-induced depolarization. Resting membrane potential of neurons treated for 48 h with DMSO (black) or 1 μm FK506 (red) in NaCl or KCl treatment groups. ***p < 0.0001; ns, non-significant; one-way ANOVA with Tukey's multiple comparison test. B, Left, Mean ± SEM of normalized 340/380 ratio of fura-2 ratiometric dye after depolarization with KCl. Right, Mean plateau value of normalized 340/380 ratio between 18 and 20 min after wash-in. Points show individual cells treated with DMSO (black) or FK506 (red). Bars show mean ± SEM of all cells in each treatment group. C, Calcineurin activity does not affect calcium influx through L-type VGCCs in neurons depolarized to −40 mV. Left, Example traces of isolated L-type VGCC currents in each treatment group. Right, Plateau current density of isolated L-type VGCCs at −40 mV during the last 10 ms of the depolarizing step in each treatment group. Points show mean of two to five repeats from individual neurons. Bars show mean ± SEM of all cells recorded. ***p < 0.0001, one-way ANOVA with Tukey's multiple comparison test.