Figure 2. Lack of effect of [Na⁺]_i on inactivation of homomeric KCNQ1.

After long (1.2 s) saturating pulses to +40 mV the biphasic deactivation was measured at tail potentials, V_t, ranging from -80 to -60 mV. Example traces (A: no [Na⁺]_i; B: 65 mm[Na⁺]_i) are at V_t= -70 mV. The time course was fitted by a bi-exponential function (eqn (1)) and mean values of the resulting time constants (C) (squares, slow time constants; circles, fast time constant) and of the ratio of the coefficients of the fast and the slow component, a_f/a_s (D) are plotted as a function of V_t. No [Na⁺]_i, ○; 65 mm[Na⁺]_i, •.