Renal expression of the essential genes associated with sodium transport following a total proctocolectomy in rats.

The water and electrolyte balance is regulated by the renin-angiotensin-aldosterone system in the kidney. We previously reported that the levels of circulating aldosterone dramatically increased following a total proctocolectomy in rats. However, there is no direct evidence regarding whether renal adaptation is accelerated by the induction of aldosterone-associated molecules. To explore this question, Sprague-Dawley rats underwent total proctocolectomies and then were killed 8 weeks later. We investigated the renal expression of 11beta-hydroxysteroid dehydrogenase type 2, the alpha-, beta-, and gamma-subunits of the epithelial sodium channel, and the alpha1- and beta1-subunits of Na+,K+-ATPase mRNAs because those molecules are responsible for the aldosterone specificity for mineralocorticoid receptor, amiloride-sensitive sodium absorption, and sodium extrusion from distal tubules, respectively. A Northern blot analysis demonstrated the kidney to exhibit mRNA induction for all of these molecules, thus supporting the idea that renal adaptation following a total proctocolectomy depends, at least in part, upon the molecular induction which is principally regulated by circulating aldosterone.