Article: article from journal or magazin.
Reducing αENaC expression in the kidney connecting tubule induces pseudohypoaldosteronism type 1 symptoms during K+ loading.
American Journal of Physiology. Renal Physiology
Genetic inactivation of the epithelial Na(+) channel α-subunit (αENaC) in the renal collecting duct (CD) does not interfere with Na(+) and K(+) homeostasis in mice. However, inactivation in the CD and a part of the connecting tubule (CNT) induces autosomal recessive pseudohypoaldosteronism type 1 (PHA-1) symptoms in subjects already on a standard diet. In the present study, we further examined the importance of αENaC in the CNT. Knockout mice with αENaC deleted primarily in a part of the CNT (CNT-KO) were generated using Scnn1a(lox/lox) mice and Atp6v1b1::Cre mice. With a standard diet, plasma Na(+) concentration ([Na(+)]) and [K(+)], and urine Na(+) and K(+) output were unaffected. Seven days of Na(+) restriction (0.01% Na(+)) led to a higher urine Na(+) output only on days 3-5, and after 7 days plasma [Na(+)] and [K(+)] were unaffected. In contrast, the CNT-KO mice were highly susceptible to a 2-day 5% K(+) diet and showed lower food intake and relative body weight, lower plasma [Na(+)], higher fractional excretion (FE) of Na(+), higher plasma [K(+)], and lower FE of K(+). The higher FE of Na(+) coincided with lower abundance and phosphorylation of the Na(+)-Cl(-) cotransporter. In conclusion, reducing ENaC expression in the CNT induces clear PHA-1 symptoms during high dietary K(+) loading.
Aldosterone/metabolism, Animals, Body Weight, Colon/metabolism, Diet, Eating, Epithelial Sodium Channels/biosynthesis, Epithelial Sodium Channels/genetics, Female, Kidney Tubules, Collecting/metabolism, Kidney Tubules, Collecting/pathology, Male, Mice, Mice, Knockout, Phosphorylation, Potassium/blood, Potassium/metabolism, Pseudohypoaldosteronism/genetics, Pseudohypoaldosteronism/metabolism, Sodium/blood, Sodium/metabolism, Solute Carrier Family 12, Member 1/biosynthesis, Solute Carrier Family 12, Member 1/genetics, Solute Carrier Family 12, Member 3/biosynthesis, Solute Carrier Family 12, Member 3/genetics
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