Kinetics of Kv7.2/7.3 channel closure. (A) Time course for current from a single voltage–clamped cell undergoing a 20-s exposure to 10 µM oxo-M. Current is steady-state measured at −20 mV. Sampling frequency: 0.25 Hz during baseline and 200 Hz during agonist. (B) Individual current traces corresponding to points in A. Voltage was stepped from −20 to −60 mV for 500 ms every 4 s. (C) Time course for normalized mean current in five cells. Note the different time scales for onset and washout. For clarity in display, points from fast sampling were pooled in 1-s bins and points from slow sampling were pooled in 20-s bins. (D) M current concentration–response time course for a single cell. Oxo-M from 1 nM to 10 μM as labeled. (E) M current concentration–response curve from steady-state values for eight cells. Mean ± SEM.