Figure 1.

Pervanadate effect on synaptic transmission. (A) Simultaneous recording of presynaptic ICa and of PSP evoked by a depolarizing presynaptic voltage clamp step (Vm). Before (control) and after pervanadate (PER) superfusion at 100 μM ICa increased and, simultaneously, PSP amplitude decreased. (B) Normalized time course of extracellular pervanadate (100 μM; arrow Per) effect on PSP (□) and ICa (▪) after 8 min the pervanadate was washed out (washout) in three different experiments (bars represent SE). (C) Pervanadate presynaptic microinjection (PER inj) using the same protocol as in A. Note that during the first 7 min pervanadate produced an increase of ICa and PSP amplitude and of the rate of rise (voltage/time), followed by a return toward control levels in 25 min. (D) Normalized time course of intracellular pervanadate effect on ICa (▪), PSP (□), and rate of rise [voltage/time (⋄)].