Effect of aldosterone on renal transforming growth factor-beta.

Aldosterone participates in the pathophysiology of several models of progressive chronic renal disease. Because of the causal connection between transforming growth factor-beta(1) (TGF-beta) and scarring in many such models, we hypothesized that aldosterone could evoke TGF-beta in the kidney. Aldosterone infusion for 3 days in otherwise normal rats caused a more than twofold increase in TGF-beta excretion without changes in systolic pressure or evidence of kidney damage. Concurrent treatment with amiloride did not alter this effect, indicating that aldosterone's stimulation of TGF-beta was independent of its regulation of sodium or potassium transport. However, concurrent treatment with spironolactone did block the increase in TGF-beta, indicating that the effect depends on the mineralocorticoid receptor. Renal mRNA for serum glucocorticoid kinase rose, but no change in TGF-beta message occurred, suggesting posttranscriptional enhancement of renal TGF-beta. In summary, aldosterone provokes renal TGF-beta, and this action may contribute to aldosterone's fibrotic propensity.