Figure 1.

NGF affects PSP but not presynaptic spike or calcium current. (A) Pre- and postsynaptic spikes from the squid giant synapse, before and after extracellular application of NGF (100 ng/ml). The postsynaptic response was markedly reduced 50 min after NGF application. No significant change in the presynaptic spike was observed. (B) Simultaneous recording of presynaptic calcium current (ICa²⁺) and PSP evoked by a depolarizing voltage-clamp step before (control) and after NGF superfusion (100 ng/ml). Note that PSP decreased in amplitude, whereas presynaptic ICa²⁺ did not change. (C) Normalized time course of the effect of 100 ng/ml of extracellular NGF on PSP (■) and ICa²⁺ (•) (1) using the same experimental protocol as in B (n = 4). Plot is the percentage of remaining PSP or ICa²⁺ at a given time; bars represent standard deviation.