Figure 3. Inhibition of I_kv by 4-aminopyridine in rat conduit PAMs.

A and B, the effect of various concentrations of 4-AP (indicated in mm) on I_kv2 and I_kv1 in two representative cells, respectively, using the experimental protocol described in the legend to Fig. 2A. Insets show current traces at times indicated by the letters. C_m was 12.7 (A) and 12 pF (B). C, concentration dependence of the block of I_kv1 (circles) and I_kv2 (squares) by 4-AP. The continuous line through the circles is drawn according to the equation described in the legend to Fig. 2B with an IC₅₀ of 0.17 mm and a residual component A equal to 0.12. Open (n = 11) and filled (n = 6) circles show normalized current in the presence and absence of 20 mm TEA, respectively. The line through the squares (n = 6) is drawn by eye. I_4-AP/I_C represents a ratio of the current in the presence of the corresponding concentration of 4-AP (I_4-AP) and control current (I_C) in the absence of the inhibitor.