Figure 3.
Interaction of verapamil with an external and an internal blocker on Kv1.3 wild-type channels. Left: currents through Kv1.3 in the absence (control) and presence of 25 μM externally-applied verapamil (Vero, bottom trace). Middle: effect of 1 nM externally-applied charybdotoxin (ChTXo) alone (middle trace) and in combination with 25 μM externally-applied verapamil (lower trace). Dashed lines show the expected reduction of currents before and after application of 25 μM verapamil in the absence of other external blockers, indicating an additional effect with ChTX in this experiment. Right: Effect of 25 μM intracellularly-applied N-methyl-verapamil (N-met-Veri) alone (top) and in combination with 25 μM externally-applied verapamil (bottom). The expected reduction of currents before and after application of 25 μM verapamil in the absence of other external blockers (dashed lines), indicates a competition of verapamil with N-met-Veri in this experiment. Internal N-met-Veri was applied through the patch pipette.