Figure 2.

Hyperaldosteronism mutations in Xenopus Na/K pumps. (A) TEVC recording at −50 mV from a Na⁺-loaded oocyte expressing wild type. Application of 10 mM K⁺ in NMG⁺_o stimulated outward current. There is zero ouabain (ouab)–sensitive steady-state current in Na⁺_o alone. (B) A similar TEVC recording from an oocyte expressing L104R, 3 d after cRNA injection. K⁺_o-induced outward current was absent, and switching from NMG⁺_o to Na⁺_o induced an inward current that was partially inhibited by perfusion of 10 mM ouabain. Vertical deflections along the current trace represent 100-ms voltage pulses to obtain I-V curves. (C) Mean ouabain-sensitive I-V plots measured in NMG⁺_o (filled symbols) and in Na⁺_o (open symbols), 3–4 d after injection, from oocytes expressing L104R (down triangles), V332G (circles), delF100-L104 (diamonds), and EETA963S (up triangles). Number of experiments is indicated in parentheses. Error bars represent SEM.