FIGURE 5.
Electrophysiological analysis of human WT and ΔPEST KIR2.1 channels transiently transfected in HEK293T cells. (A) Representative current traces of WT and ΔPEST IKIR2.1 recorded in whole cell mode. (B) Normalized current–voltage relation curve of WT and ΔPEST IKIR2.1 (mean ± SEM; WT n = 18, ΔPEST n = 18), note that error bars are smaller than symbols at each point. (C) Steady state IKIR2.1 traces from WT and ΔPEST channel containing excised inside–out patches elicited by a voltage ramp protocol from -100 to + 100 mV over 5 s, under baseline conditions (black) and upon application of 5 μM spermine (red). (D,E) Quantification of rectification index (inward current at –80 mV divided by outward current at +50 mV) of WT and ΔPEST IKIR2.1 from ramp protocol elicited currents in inside-out mode without (D, baseline) and in the presence of 5 μM spermine (E) (mean ± SD, WT n = 10, ΔPEST n = 10). (F) Quantification of normalized outward current (at +50 mV) from WT and ΔPEST channels in inside-out patch clamp under baseline conditions and with increasing spermine concentrations. P < 0.01 vs. WT; ****P < 0.0001 vs. baseline (mean ± SD, WT n = 10, ΔPEST n = 10).