Subcellular distribution of L-type VDCCs in hippocampal neurons visualized by STBodipy-DHP. Confocal images were taken from 4 DIV hippocampal neurons cultured in the absence (D) and presence (E,F) of 10 ng/ml bFGF from 2 DIV.A–C show phase-contrast photographs of the same neurons in D–F, respectively.G–I show the neurites of neurons inA–C, respectively, at higher magnification, andJ–L represent corresponding fluorescence images. Note that several fluorescent “hotspots” are observed along the neurites in bFGF-treated neurons, which overlap with the branch points or varicosities. No such fluorescent hotspots are observed on the neurites of control neurons. Scale bars in D and inJ represent 25 μm and 10 μm, respectively.M, Quantification of L-type VDCCs on the neurites of hippocampal neurons (see Results for details). The amount of L-type VDCCs on the neurites is increased in bFGF-treated neurons (n = 5, hatched bar), compared with control neurons (n = 5, open bar). *p < 0.01 versus control (Student’st test).