Fig. 5.

Increase of current by NS1643 is slow for I567A hERG1 channels. Currents were elicited every 10 s with a 1-s pulse to −10 mV. Outward current at the end of each pulse was plotted as a function of pulse number for a 5-min control period and during the initial 10 min after addition (marked by arrow) of 30 μM drug to the perfusate. WT currents reached an approximate steady-state within ∼5 min, whereas I567A mutant channel current increased monotonically throughout the 10-min period of measurement.