Effect of 0.1 μ
M E-4031 on the fast and slow component of the deactivation current. (A) Original currents at −45 mV in control and in 0.1 μ
M E-4031 applied for 4 min. Holding potential −20 mV, cell diameter 64 μm, temperature 33°C. Double exponential fits with eq (1) superimposed, starting 16 ms after beginning of pulse. Fit parameters:
(B) Inhibition of K1 (=initial amplitude of slow component) and K3 (=initial amplitude of fast component) at −55 mV plotted against concentration of E-4031;
n=3–5 per point. Values for K1 fitted with dose-response curve. Parameters: Maximum inhibition=82.5%, IC
50=38.1 n
M, Hill coefficient=1.70.