Recovery from paxilline inhibition is faster at higher Po. (A) Unblock time constant from washout of paxilline is comparable to unblock during change in equilibration conditions. The panels are all from the same patch, with the unblocking time course examined at 0 (top), 40 (middle), or 80 mV (bottom). Black symbols and fitted line correspond to unblock in the constant presence of 100 nM paxilline after a change in equilibration condition from −80 mV, 300 µM Ca²⁺ to each of the three voltages. Red symbols and fitted red lines correspond to washout of paxilline at the indicated voltage with 300 µM Ca²⁺. BK availability was assessed with brief test steps to 160 mV. Po during the recovery conditions was estimated from G-V curves as 0.7 (0 mV, top), ∼0.85 (40 mV, middle), and ∼0.9 (80 mV, bottom). (B) Recovery time course was compared in the same patch for washout of paxilline at 0 (Po of ∼0.7), −40 (Po of ∼0.4), and −80 mV (Po of ∼0.1), all in 300 µM Ca²⁺. (C) Recovery time course from A (middle) for washout of paxilline is plotted on a logarithmic scale along with fits of an exponential of form I(t) = (1 − exp(−t/tau)ⁿ, for n = 1, 2, or 4. (D) Open circles show recovery time constants for patches examined as in A, with closed symbols corresponding to time constants measured during paxilline washout, and open circles corresponding to the constant presence of paxilline, with each point reflecting the mean of at least four patches. Closed diamonds correspond to time constants measured as in B. The fitted G-V curve (V_h = −34.0 mV; z = 0.98) for currents activated in the patches in A and B is shown to highlight the extent of changes in fractional activation for the different recovery conditions. Red symbols correspond to seven patches for which recovery was measured at 0 mV in the constant presence of either 100 nM paxilline (red square) or 20 nM paxilline (red circle).