Figure 2. Effect of treatment with recombinant Klotho protein on current in KCNQ1/KCNE1 expressing Xenopus oocytes. (A) Original tracings demonstrating outward K⁺ currents activated by depolarization from -120 to +80 mV in 20 mV steps from a holding potential of -80 mV in Xenopus oocytes injected with water (1),or injected with cRNA encoding KCNQ1/KCNE1 without (2) or with (3) a 24 h pretreatment with recombinant Klotho protein (30 ng/ml). (B) Arithmetic means ± SEM (n = 4–17) of the normalized depolarization-induced K⁺ current at +80 mV in Xenopus oocytes injected with water (dotted bar), or with cRNA encoding KCNQ1/KCNE1 without (white bar) or with (black bar) a 24 h pretreatment with recombinant Klotho protein (30 ng/ml). *** indicates statistically significant (P < 0.001) difference of Klotho treated KCNQ1/KCNE1 expressing Xenopus oocytes from untreated KCNQ1/KCNE1 expressing oocytes. (C) Arithmetic means ± SEM (n = 4–17) of the normalized depolarization-induced K⁺ current as a function of voltage in Xenopus oocytes injected with water (gray triangles), or with cRNA encoding KCNQ1/KCNE1 without (white circles) or with (black circles) a 24 h pretreatment with recombinant Klotho protein (30 ng/ml). *** indicates statistically significant (P < 0.001) difference of Klotho treated KCNQ1/KCNE1 expressing Xenopus oocytes from untreated KCNQ1/KCNE1 expressing Xenopus oocytes. (D) Arithmetic means ± SEM (n = 15–17) of the depolarization-induced K⁺ current (normalized to the maximum peak current of each respective group) as a function of voltage in Xenopus oocytes injected with cRNA encoding KCNQ1/KCNE1 without (white circles) or with (black circles) a 24 h pretreatment with recombinant Klotho protein (30 ng/ml).