Biophysical properties of the cumulative inactivation of K⁺ currents in Raw macrophages. (A–C) Representative traces showing cumulative inactivation of K⁺ currents. Cells were held at −80 mV, and currents were elicited by a train of eight depolarizing voltage steps (200-ms duration) to +60 mV once every 400 ms. (A) Control. (B) LPS. (C) DEX. (D) Percentage of cumulative inactivation at the peak current. The percentage was calculated as a result of the difference between the peak current at the first pulse and the remaining current at the last. (E) Plot of normalized current area versus pulse. The current amplitude became progressively smaller from the first trace to the last in control and LPS, but not in DEX-treated macrophages. Inset represents K⁺ current area decay from control and DEX-treated macrophages for magnification. Values are the mean ± SEM of at least 10 independent cells. **, P < 0.01 versus control (Student’s t test).