Fig. 4.

Partial block of Na- and Cs-mediated currents by QX-314. A: currents in a rat DRG neuron in control (black), after applying 1 μM capsaicin (red), and immediately (∼100 ms) after switching to a solution with 10 mM QX-314 added to the same 1 μM capsaicin-containing external solution (blue). Current-voltage relationships were determined from a 100-ms downward-going ramp from +100 to −100 mV (following 200 ms at +100 mV to inactivate voltage-dependent sodium currents maximally). Voltage protocols were delivered every second from a steady holding potential of −80 mV. B: continuation of the experiment in A showing currents 160 s after adding 10 mM QX-314 to the external solution (green) and immediately after changing to a QX-314-free solution (violet). C: time course of block and recovery from block by externally applied QX-314 for the experiment in A and B.