Aldosterone-dependent and -independent regulation of Na and K excretion and ENaC in mouse kidney.

Aldosterone-dependent and -independent regulation of Na and K excretion and ENaC in mouse kidney. Am J Physiol Renal Physiol. 2020 Jul 06;: Authors: Yang L, Frindt G, Xu Y, Uchida S, Palmer LG Abstract We investigated the regulation of Na+and K+ excretion and ENaC in mice lacking the gene for aldosterone synthase (AS), using clearance methods to assess excretion and electrophysiology and Western blotting to test for ENaC activity and processing. After one day of dietary Na restriction AS-/- mice lost more Na+ in the urine than did AS+/+. After 1 week on this diet both genotypes strongly reduced urinary Na+ excretion, but creatinine clearance decreased only in AS-/- mice. Only AS+/+ animals exhibited increased ENaC function, assessed as amiloride-sensitive whole-cell currents in collecting ducts or the cleavage of α and γENaC in Western blots. To assess the role of aldosterone in the excretion of a K load, animalswere fasted overnight and re-fed with high-K or low-K diets for 5 hours. Both AS+/+ and AS-/- mice excreted a large amount of K+ during this period. In both phenotypes the excretion was benzamil-sensitive, indicating increased K+secretion coupled to ENaC-dependent Na+reabsorption. However the increase in plasma K+under these conditions was much larger in AS-/- than in AS+/+ animals. In both groups cleavage of αENaC and γENaC increased. However INameasured ex vivo in CNTs was enhanced only in AS+/+. We conclude that in the...
Source: Am J Physiol Renal P... - Category: Urology & Nephrology Authors: Tags: Am J Physiol Renal Physiol Source Type: research