Fig. 6.
DYRK2 stimulates ENaC currents in outside-out patches excised from the apical membrane of principal cells in split open microdissected mouse renal tubules. a and b Representative current traces from whole-cell (left panels) and subsequent outside-out (right panels) patch-clamp recordings at a continuous Vhold of − 60 mV. Black bars indicate the presence of amiloride (Ami, 2 μM) in the bath solution. Active recombinant DYRK2 (40 U/ml; a) or heat-inactivated DYRK2 (inactive DYRK2; b) were included in the pipette solutions as indicated under the traces. c–e Summary of data from similar experiments as shown in the representative traces (a and b, left panels) with DYRK2 (n = 9) or inactive DYRK2 (n = 14) in the pipette solution. In c and d, black dots correspond to measurements from individual patches, and open columns with error bars represent mean values ± SEM. ∆IAmi values shown in c were determined in the whole-cell configuration. Data shown in d represent ∆IAmi values from outside-out patches (∆IAmi(o/out)) expressed as percentage of the corresponding whole-cell ∆IAmi values (% of ∆IAmi (w/c)). DYRK2, n = 9; inactive DYRK2, n = 14. In c and d, statistical significance was assessed by unpaired Student’s t-test and unpaired Student’s ratio t-test, respectively. e Averaged normalized ΔIAmi recorded in outside-out patches as illustrated in a (right panel) at different times after patch excision with DYRK2 (solid triangles, n = 9) or inactive DYRK2 (open circles, n = 14) in the pipette solution. In e, ∆IAmi values determined at individual time points were compared with the corresponding initial ∆IAmi value at 2 min using paired Student’s ratio t-test. * p < 0.05; ** p < 0.01; n.s. not significant