Figure 8.

PIP2 enhances the effect of retigabine on KCNQ channel voltage activation. For these experiments, KCNQ currents were measured at various test potentials elicited by a 1 s depolarization from −85 mV and were followed by a return step to −70 mV. Test potentials ranged from −115 mV to +15 mV in 10-mV increments. (a) Top panels: representative current traces from −85 mV to −35 mV from heterologous cells expressing KCNQ2/3, KCNQ5, and KCNQ3^A315T in the absence or presence of 40 μM retigabine. Bottom panels: summary data of the current-to-voltage relationship of KCNQ2/3 (n = 8; V_0.5 = −27 ± 1 mV, slope factor = 10 ± 0.9; +retigabine V_0.5 = −68 ± 1 mV, slope factor = 11 ± 1), KCNQ5 (n = 10; V_0.5 = −43 ± 2 mV, slope factor = 9 ± 0.9; +retigabine V_0.5 = −67 ± 2 mV, slope factor = 13 ± 1), or KCNQ3^A315T (n = 5; V_0.5 = −35 ± 2 mV, slope factor = 9.5 ± 1; +retigabine V_0.5 = −89 ± 3 mV, slope factor = 8 ± 2) in the absence or presence of 40 μM retigabine. (b) Top panels: representative current traces from −85 mV to −35 mV from heterologous cells expressing PIPKIγ90 and either KCNQ2/3, KCNQ5, or KCNQ3^A315T in the absence or presence of 40 μM retigabine. Bottom panels: summary data of the current-to-voltage relationship of KCNQ2/3 (n = 6; V_0.5 = −52 ± 2 mV, slope factor = 10 ± 2; +retigabine V_0.5 = −88 ± 3 mV, slope factor = 8 ± 2), KCNQ5 (n = 5; V_0.5 = −54 ± 6 mV, slope factor = 13 ± 2; +retigabine V_0.5 = −70 ± 4 mV, slope factor = 17 ± 1), or KCNQ3^A315T (n = 5; no fit, just a line through the points) in the presence or absence of retigabine. Data represent means ± error of the mean. To see this figure in color, go online.