Amiloride-sensitive transepithelial potential difference is reduced and αENaC is present in the luminal cell membrane of the renal collecting system of sgk1^–/– mice on a low-NaCl diet. (a) Transepithelial potential difference (PD) in isolated perfused collecting ducts at day 3 after initiating a low-NaCl diet (0 g Na⁺/kg) in the absence (n = 12–16 ducts in 3–5 mice) (white bar) and presence (n = 4–5 ducts in 3–5 mice) (black bar) of 10 μM amiloride. *P < 0.05 versus sgk1^+/+ mice. (b) Immunohistochemical localization of αENaC in renal connecting tubule profiles at day 3 after initiating a low-NaCl diet (0 g Na⁺/kg). Arrowheads indicate apical localization of αENaC.