Electrophysiological parameters of WT and mutants Kv7.1 channels

Activation curves were fit to a Boltzmann distribution, G/Gmax = 1/{1+exp[(V50-V)/s]}, where V50 is the voltage at which the current is half-activated and s is the slope factor. V50s were determined in the absence of Cd2+. Data are expressed as mean±SEM and in parentheses are indicated the number of cells. *, p<0.05 **, p<0.01 vs. WT, (one way ANOVA followed by Dunnett's Multiple Comparison Test). To determine the Iinst/Imax ratio and the rectification index, oocytes were recorded in the absence (−Cd2+) or presence of 100 µM Cd2+ (+Cd2+). The Iinst/Imax ratio has been calculated by the ratio of the instantaneous current at the beginning of the pulse at +40 mV (Iinst) that follows the capacitive transient and the current at the end of the pulse at +40 mV (Imax). The larger is this ratio, the larger is the instantaneous open component. #, p<0.05, ##, p<0.01 +Cd2+ versus −Cd2+ (two-tailed, Student's paired t test). The rectification index corresponds to the ratio of the current amplitude measured at −140 mV to that measured at −5 mV. The larger is this ratio, the stronger is the constitutive open leak K+ current component. Due to lack of space, are shown only the means (without SEMs) of the rectification index for the same number of tested cells indicated in parentheses.