Mineralocorticoids modulate the expression of the b-3 subunit of the Na+, K+ - ATPase in the renal collecting duct

Abstract

Renal sodium reabsorption depends on the activity of the Na+,K+-ATPase / heterodimer. Four ((1-4)) and 3 ((1-3)) subunit isoforms have been described. It is accepted that renal tubule cells express (1)/(1) dimers. Aldosterone stimulates Na+,K+-ATPase activity and may modulate (1)/(1) expression. However, some studies suggest the presence of (3) in the kidney. We hypothesized that the (3) isoform of the Na+,K+-ATPase is expressed in tubular cells of the distal nephron, and modulated by mineralocorticoids. We found that (3) is highly expressed in collecting duct of rodents, and that mineralocorticoids decreased the expression of (3). Thus, we describe a novel molecular mechanism of sodium pump modulation that may contribute to the effects of mineralocorticoids on sodium reabsorption.