Chloroquine unblock depends on drug concentration. A to D, top panels, currents were elicited in various chloroquine concentrations by blocking at +70 mV and unblocking at −70 mV Kir6.2/SUR2A, and Kir6.2(N160D)/SUR2A, as indicated. Bottom panels, the first 250 ms of the chloroquine unblock time course are displayed. E, concentration dependence of the half-time (t1/2) needed for chloroquine unblock.