Regulation and function of adrenal renin-angiotensin system.

In order to explore the role of adrenal renin-angiotensin system in the regulation of aldosterone biosynthesis we measured plasma renin activity (PRA)(ng/ml/h) and aldosterone (pg/ml), adrenal renin (AR) activity (ng/ml/h/mg tissue protein), adrenal renin, aldosterone synthase(AS) and 11β-hydroxylase(11β-OH) cytochrome P450 mRNA in the zona glomerulosa in control conditions (n=15) and 48 hours after bilateral Nx, N=23, Nx combined with low salt diet (Nx+LSD), N=26, and with the additional administration of Losartan(10mg/kg/die)(Nx+LSD+Los), N=26, in 12 week-old male Sprague-Dawley rats. Adrenal renin mRNA was assessed by rt-PCR, AS and 11β-OH by Northern blot with a specific oligonucleotide as % of control using densitometric analysis and GAPDH as a standard for gene expression. PRA fell to undetectable levels after Nx. 11β-OH was not affected by any of these maneuvers. These results demonstrate that adrenal renin is modulated by sodium balance, selectively regulates aldosterone biosynthesis through the AT1 receptors and this action is independent from circulating renin of renal origin.