Figure 2.

Rescue of spontaneous synaptic activity in BoNT/A-silenced synapses by elevated extracellular Ca²⁺ requires VGCCs. (A) Representative whole-cell recordings and mean mEPSC frequencies from non-intoxicated cultures in the presence of 2, 4, 8, or 16 mM Ca²⁺. Representative whole-cell recordings and mean mEPSC frequencies from BoNT/A-intoxicated cultures, in the presence of 2, 4, 8, or 16 mM Ca²⁺ as well in 16 mM Ca²⁺ with VGCC antagonists (10 µM nimodipine, 0.5 µM ω-agatoxin IVA and 0.5 µM ω-conotoxin MVIIC). (C) Representative whole-cell recordings and mean mEPSC frequencies from neurons intoxicated by BoNT/D or BoNT/E and incubated in 2 or 16 mM Ca²⁺. mEPSC frequencies are normalized to recordings from age-matched, non-intoxicated control cultures. Scale bars represent 5 s (x-axis) and 40 pA (y-axis). All data presented as mean ± SEM and n ≥ 10 neurons for all conditions. **Indicates p < 0.01, ***Indicates p < 0.001.