Effects of intrarenal angiotensin 1-7 infusion on renal haemodynamic and excretory function in anaesthetised two-kidney one-clip and deoxycorticosterone acetate-salt hypertensive rats.

This study investigated the action of angiotensin 1-7 (Ang (1-7)) on renal haemodynamic and excretory function in the two-kidney one-clip (2K1C) and deoxycorticosterone acetate (DOCA)-salt rat models of hypertension, in which the endogenous renin-angiotensin system (RAS) activity was likely to be raised or lowered, respectively. Rats were anaesthetised and prepared for the measurement of mean arterial pressure and kidney function during renal interstitial infusion of Ang (1-7) or saline. Kidney tissue concentrations of angiotensin II (Ang II) and Ang (1-7) were determined. Intrarenal infusion of Ang (1-7) into the clipped kidney of 2K1C rats increased urine flow (UV), absolute (U V) and fractional sodium (FE ) excretions by 110%, 214% and 147%, respectively. Renal Ang II concentrations of the clipped kidney were increased with no major changes in Ang (1-7) concentration. By contrast, Ang (1-7) infusion decreased UV, U V, and FE by 27%, 24% and 21%, respectively in the non-clipped kidney in which tissue Ang (1-7) concentrations were increased, but renal Ang II concentrations were unchanged compared to sham animals. Ang (1-7) infusion in DOCA-salt rats had minimal effects on glomerular filtration rate but significantly decreased UV, U V and FE by ∼30%. Renal Ang (1-7) concentrations were higher and Ang II concentrations were lower in DOCA-salt rats compared to sham rats. These findings demonstrate that the intrarenal infusion of exogenous Ang (1-7) elicits different renal excretory responses the magnitude of which is dependent on the balance between the endogenous renal Ang II-AT receptor axis and Ang (1-7)-Mas receptor axis.