Figure 2. A decrease in osmolarity stabilizes the channel open state (37°C).

A, representative perforated-patch recordings of the KCNE1–KCNQ1 current measured in hyper- (hyper), iso- (iso) and hypoosmolar (hypo) solutions, in the same cell. Inset: voltage-clamp protocol used. Voltage was stepped from a holding potential of −80 mV to various voltages (4 s) between −20 mV and +80 mV in 20 mV increments, and then to −40 mV (1 s). B, effect of osmolarity on the mean tail-current density (left), the half-activation potential (V_0.5; middle) and the deactivation time constant at −40 mV (τ_deact; right) of KCNE1–KCNQ1 (n = 10). Tail current was measured at −40 mV after a 4 s pulse to +80 mV. V_0.5 was calculated by a Boltzmann fit of the activation curve. *P < 0.05, ***P < 0.005 (one-way ANOVA for repeated measures).