Figure 3. Effect of β-glucuronidase inhibitor (DSAL) on current in KCNQ1/KCNE1 and Klotho 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 in Xenopus oocytes injected with water (1), injected with cRNA encoding KCNQ1/KCNE1 alone (2) and in Xenopus oocytes injected with cRNA encoding both KCNE1/KCNQ1 and Klotho in the absence of β-glucuronidase inhibitor (3), or in the presence of DSAL for 24 h (4) or 48 h (5). (B) Arithmetic means ± SEM (n = 9–23) of the normalized depolarization-induced K⁺ current at +80 mV in Xenopus oocytes injected with water (dotted bar), injected with cRNA encoding KCNQ1/KCNE1 alone (white bar) or injected with cRNA encoding both KCNQ1/KCNE1 and Klotho in the absence of β-glucuronidase inhibitor DSAL (black bar), or in the presence of DSAL for 24 h (first gray bar) or 48 h (second gray bar). ** indicates statistically significant (P < 0.01) difference of Klotho and KCNQ1/KCNE1 expressing Xenopus oocytes from Xenopus oocytes expressing KCNQ1/KCNE1 alone. ## indicates statistically significant (P < 0.01) difference of DSAL-treated from untreated KCNQ1/KCNE1 and Klotho expressing Xenopus oocytes. (C) Arithmetic means ± SEM (n = 9–23) of the normalized depolarization-induced K⁺ current as a function of voltage in Xenopus oocytes injected with water (gray triangles), injected with cRNA encoding KCNQ1/KCNE1 alone (white circles) and in Xenopus oocytes injected with cRNA encoding both KCNQ1/KCNE1 and klotho in the absence of β-glucuronidase inhibitor DSAL (black circles), or in the presence of DSAL for 48 h (black triangles). ** indicates statistically significant (P < 0.01) difference of Klotho and KCNQ1/KCNE1 expressing Xenopus oocytes from Xenopus oocytes expressing KCNQ1/KCNE1 alone. (D) Arithmetic means ± SEM (n = 18–23) of the depolarization-induced K⁺ current (normalized to the maximum peak current of each group) as a function of voltage in Xenopus oocytes injected with cRNA encoding KCNQ1/KCNE1 and Klotho without treatment (white circles) or treated for 48 h with DSAL (black circles).