Fig. 7.

Soluble LN stimulates a rapid increase of [Ca²⁺]_i in surgically isolated filopodia. a, Filopodia with resting [Ca²⁺]_i <100 nm responded with a rapid rise of [Ca²⁺]_i to bath-applied LN (20 μl, 20 μg/ml). LN was added att = 2 min (arrow), and significant increases in [Ca²⁺]_i were measured att = 4 min. Three representative isolated filopodia are shown (filled symbols). Identical concentrations of soluble FN had no effect (open triangles). b, Filopodia with resting [Ca²⁺]_i >100 nm also responded to soluble LN (t = 2 min) with a rapid increase of [Ca²⁺]_i(t = 4 min). Data from three representative isolated filopodia are plotted (filled symbols). As a control, the addition of soluble FN has no effect on [Ca²⁺]_i (open triangles). Substrate of neuronal culture = FN.