Concentration-dependent effects of NFA on ISlo2.1 magnitude and kinetics. (A) I-V relationships determined before (control) and after treatment of oocytes with 1, 3, and 6 mM NFA as indicated. (B) G-V relationships based on I-V relationships plotted in A. Data were fitted with a Boltzmann function (smooth curves) to determine the half-point (V1/2) and effective valence, z, for ISlo2.1 activated by treatment of oocytes with NFA. The V1/2 was −1 ± 0.7 mV (n = 8), −43 ± 2.4 mV (n = 7), and −84 ± 6 mV (n = 5) for 1, 3, and 6 mM NFA, respectively. The z values were 0.71 ± 0.01, 0.57 ± 0.02, and 0.46 ± 0.02 for oocytes treated with 1, 3, and 6 mM NFA, respectively. (C) Kinetics of ISlo2.1 activated by NFA. A summary of the fast and slow time constants (τfast and τslow) for activation of the time-dependent component of current (n = 15 for 1 mM NFA and n = 14 for 3 mM NFA). (D) A plot of the amplitude of the instantaneous current (Iinst) divided by total outward current (Itotal) as a function of text potential, Vt (n = 14–15).
