Figure 6.

Stimulatory effect of Flu on M-type K⁺ current (I _K(M)) in NSC-34 cells. In these experiments, cells were bathed in Ca²⁺-free Tyrode's solution and the pipette was filled with a K⁺-containing solution. (A) Current traces obtained in the absence (a) and presence of 1 and 3 μM Flu. The inset indicates the voltage protocol used. (B) Summary of the data showing effects of Flu and linopirdine on I _K(M) measured at −50 mV (left) and −20 mV (right) in NSC-34 cells (mean ± SEM; n = 10–13 for each point). Flu: flupirtine; Lino: linopirdine. *Significantly different from controls. **Significantly different from Flu (3 μM) alone group. (C) Voltage dependence of I _K(M) activation in the absence (■) and presence (□) of 3 μM Flu (mean ± SEM; n = 7–10 for each point). The smooth dashed lines represent the best fits to the Boltzmann equation described in Section 2. Notably, addition of Flu can shift the activation curve of I _K(M) to the hyperpolarizing voltage with no change in the gating charge of this current.