Fig. 5

Long-lasting openings observed in macroscopic and microscopic currents of wild type (WT)-CFTR. a A representative of WT-CFTR showing long-lasting openings after a rapid removal of 5 mM ATP. b Single channel current recordings obtained from a patch containing three active WT-CFTR channels (upper panel). One of the channels remains open for more than 1 min after the removal of ATP whereas the other two channels close within 1 s (upper panel). The lower panel shows amplitude histograms from the sections (a) and (b) in the single channel current data shown in the upper panel. All the three WT-CFTR channels in normal gating mode showed the almost same single channel conductance of 0.60 pA [section (a)]. Then one of the three channels went into the long-lasting opening state and its single channel conductance was 0.61 pA [section (b)]. Although we cannot know which of the three channels went into the long-lasting opening state, the single channel conductance should not be significantly changed because all three channels have the same single channel conductance of 0.60 pA, anyway