FIGURE 1.

Neuritin increases I_A densities and Kv4.2 expression via the Ca²⁺/CaN pathway. A, effects of CaN inhibitor CsA, FK520, or CaM blocker CMZ on neuritin-induced I_A densities in mouse CGNs. I_A was evoked by 200 ms of depolarization to +40 mV from a holding potential of −100 mV. CsA, FK520, and CMZ were applied for 2 h prior to initiating treatment with neuritin and then remained in the culture during the entire duration (24 h) of treatment with neuritin (150 ng/ml). B, effects of CsA, FK520, or CMZ on neuritin-induced expression of Kv4.2 protein examined by Western blotting. C, effects of CsA, FK520, or CMZ on neuritin-induced expression of Kv4.2 mRNA level as measured by quantitative RT-PCR. The data were obtained from five independent experiments. D, effect of neuritin on intracellular Ca²⁺ levels was imaged, and statistical analysis was performed before (basal) and after 27 mm KCl depolarization (high K⁺). Changes in the fura-2 fluorescence excitation ratios with increasing [Ca²⁺] are depicted from purple to red. Scale bar, 30 μm. ***, p < 0.001 for two groups connected with a straight line by unpaired t test or one-way ANOVA followed by Fisher's post hoc test.