Essentially complete recovery from paxilline block can occur, even in the continuous presence of paxilline under conditions of high Po. (A) The indicated test-pulse sequence was applied every 1 s while holding at −80 mV with 300 µM Ca²⁺. The traces show before paxilline application, after ∼50% inhibition by paxilline, and during the full paxilline effect. (B) For the same patch in A, the equilibration conditions were altered to 80 mV with 300 µM Ca²⁺ while still in the continuous presence of 100 nM paxilline. Brief sojourns to −80 mV with test steps to 160 mV were used to monitor recovery in the presence of paxilline. A 60-s washout of paxilline confirmed that no additional recovery occurred. (C) The time course of onset and recovery from inhibition by 100 nM paxilline, while in the continuous presence of paxilline, is plotted for the cell shown in A and B, with the numbers corresponding to the approximate times of the traces in A and B.