Fig. 1. Epithelial Na⁺ channel (ENaC) currents revealed by single channel recording from cultured M1 cells. (A) In a cell-attached recording, inward currents were recorded when the pipette voltage (V_p) was held at +20 mV and +40 mV. (B) In an inside-out recording, the single channel currents were detected when the pipette voltage was held at +100 mV and +60 mV. (C) In an outside-out recording, the currents were monitored when the pipette voltage was held at –60 mV. Bath application of 5 µmol l^–1 amiloride almost abolished the ENaC currents. The currents were reversed when amiloride was washed off. c indicates the closing level.