Figure 6. 4-AP occludes the boosting effect of SNX.

(A) Time course of the normalized EPSP amplitude (mean ± s.e.m., n = 9) for baseline in 4-AP and apamin, and during wash-in of SNX as indicated above. Inset shows average of 18 EPSPs taken from indicated shaded time points in 4-AP and apamin (baseline; black) and 14–20 min after SNX wash-in (red); shaded areas are ± s.e.m. Scale bars: 1.0 mV and 25 ms. (B) Scatter plot of relative EPSP peak in SNX compared to baseline in 4-AP from the individual slices in panel A. Horizontal bar reflects mean response. (C) SNX does not block 4-AP sensitive A-type current (I_A) measured in voltage clamp. Slices were bathed in nominally Ca²⁺-free aCSF containing TTX (1 µM) and Mn²⁺ (2 mM). In whole cell voltage clamp, A-type outward currents were elicited with 1 s depolarization to 40 mV from a holding potential of −80 mV followed by repolarization to −20 mV. Representative traces of outward current in control (black), subsequent addition of SNX (red) and SNX plus 4-AP (blue). Inset: 4-AP sensitive current in control (black) and SNX (red). Scale bars: 1 nA and 20 ms. (D) Scatter plot of individual slices for relative 4-AP sensitive I_A current in SNX. Horizontal bar reflects mean response.