Sodium channel currents in lamina I/II neurons are potently and completely blocked by TTX. Voltage clamp recordings of sodium channel currents using the ESI technique on lamina I/II neurons from P6 to P9 Wistar rats. A) Representative time course of normalized peak sodium channel currents during depolarizations to -20 mV elicited every 10 seconds. Perfusion of 10 nM and 30 nM TTX caused a robust inhibition of sodium channel currents. B) Representative sodium channel current traces from specific time points (as labeled) in the time course shown in A. C) Concentration-response relationship for TTX. n = 3 to 5 for all data points. LJP = 4.2 mV, uncorrected.