A, open times. τof and τos denote mean fast and slow open times, respectively. With K+ as the permeating ion, both open times were longer than with Na+ as the permeating ion. B, open probability, Po. The Po values were determined from cumulative open-time histograms including the openings of all amplitude classes. Each histogram contains between 259 and 920 individual openings and each data point contains data from three to six patches.