Diuresis and natriuresis produced by long term administration of a selective Angiotensin-(1-7) antagonist in normotensive and hypertensive rats.

Abstract In this study we evaluated the renal effects of chronic administration of the selective Angiotensin-(1–7) [Ang-(1–7)] antagonist, A-779, in normotensive and spontaneously hypertensive rats (SHR). Male adult SHR and Wistar rats were housed in metabolic cages with tap water and standard chow, for three–five days before starting infusion (Alzet osmotic mini-pumps) of A-779 (Wistar: 1 μg/h, n =9; 2.5 μg/h, n =6; SHR: 2.5 μg/h, n =6) or vehicle (0.9% NaCl – 1 μl/h, n =7 and n =10 for SHR and Wistar rats, respectively). Urine volume, water and food intake and urinary Na + were measured daily. On the last day of infusions mean arterial pressure (MAP) was recorded and urine and blood samples were collected to determine renal function parameters. Chronic infusion of A-779 produced a sustained increase in diuresis in normotensive rats [seventh day values: 0.75±0.08 ml/h (1 μg/h) and 0.94±0.13 ml/h (2.5 μg/h) vs. 0.42+0.03 ml/h for the control group, P P + excretion (1.49+0.14 mEq, 1 μg/h vs. 2.37±0.22 mEq, 2.5 μg/h, P + . In SHR, urinary Na + excretion was also increased by A-779 (2.21±0.46 mEq vs. 0.94±0.22 mEq for the control group, P