Figure 4.

Partial dose–response curves for inhibition of I_Na by 0.3–3 μM V102862 (open symbols) and 100 and 300 μM PHT (solid symbols) taken in the same hippocampal neuron at different holding membrane voltages of −60, −70, −80 and −90 mV. Partial, two point inhibition–concentration curves for PHT are consistently shifted to the right for all holding voltages tested (from −60 to −90 mV), indicating significantly (10- to 30-fold) lower potency of the drug as compared to V102862. Similar shifts in potencies were measured in seven more neurons.