Fig. 4.
Multichannel conductance as a function of AmPrβCD concentration in the cis side of the chamber. (A) A typical titration curve in 1 M KCl. The current record was filtered by averaging over 500-msec intervals. Certain roughness in the steady-state conductance levels before and after AmPrβCD addition is due to the complicated PA63 kinetics as well as the finite number of the channels in the membrane. (B) AmPrβCD inhibitory concentration depends on KCl bulk concentration, giving IC50 as 0.55 nM, 0.22 μM, and 19.3 μM for 0.1 M, 1.0 M, and 2.5 M KCl solutions, correspondingly. The applied voltage was +20 mV.