Effect of selective angiotensin antagonists on the antidiuresis produced by angiotensin-(1-7) in water-loaded rats

Abstract

In the present study we evaluated the nature of angiotensin receptors involved in the antidiuretic effect of angiotensin-(1-7) (Ang-(1-7)) in water-loaded rats. Water diuresis was induced in male Wistar rats weighing 280 to 320 g by water load (5 ml/100 g body weight by gavage). Immediately after water load the rats were treated subcutaneously with (doses are per 100 g body weight): 1) vehicle (0.05 ml 0.9%

Nonpeptide AVE 0991 Is an Angiotensin-(1–7) Receptor Mas Agonist in the Mouse Kidney

“…19 It has been shown that Ang-(1-7) increases osmotic water permeability in isolated toad skin, 20 a tissue with functional properties similar to those of the distal mammalian nephron. 21 This finding is in keeping with the antidiuretic action of Ang-(1-7) in rats 9,10,18 and in mice. 13 Moreover, it was demonstrated recently that Ang-(1-7) but not Ang IV produces a significant dose-dependent increase in water permeability in the IMCDs accompanied by an increase in cAMP levels.…”

“…A similar effect of AT 1 blockade was observed previously for Ang-(1-7) in rats. 18 An interference of AT 1 /AT 2 blockade with the water reabsorption in the peritoneum is unlikely, considering that they did not decrease water diuresis when given alone. Among other possibilities to explain the interference of AT 1 and AT 2 antagonists with the AVE 0991 effect are the existence of oligomers, 23,24 including Mas-Mas sensitive to AT 1 or AT 2 antagonists or AT 1 -Mas, AT 2 -Mas, or AT 1 -AT 2 -Mas oligomers or cross-talk mechanisms, 25 as described for the AVP V 2 receptor.…”

“…13,18 Drugs were administered in the same injection with water load at prefixed volumes (0.01 mL/g BW). In the first set of experiments, WT mice (C57BL/6, control group) or Mas-KO mice were treated with: (1) 0.58 nmol/g AVE (nϭ9, control; nϭ11, Mas-KO mice); or (2) vehicle for AVE (10 Ϫ2 mol/L KOH, 0.01 mL/g; nϭ9, control; nϭ9, Mas-KO).…”

Role of Mas receptor antagonist (A779) in renal hemodynamics in condition of blocked angiotensin II receptors in rats

“…When Ang 1-7 and A779 were used at equimolar doses, Ang 1-7 antagonist failed to block Ang 1-7-induced depressor response against AT1R blockade; suggesting that Ang 1-7 may act via the AT2R (43). Therefore, there is a complex interaction between RAS receptors (4, 6), and some actions of Ang 1-7 may also be blocked by AT1R (1,5) or AT2R antagonists (9); suggesting a crosstalk between the MasR and Ang II receptors (20). Other data indicated that the antidiuretic effect of AVE0991 that mimics the effects of Ang 1-7 was completely blocked by PD123319 and partially blocked by losartan (43).…”

Angiotensin-(1-7) increases osmotic water permeability in isolated toad skin

“…In waterloaded rats it produces marked antidiuresis (3) by a direct effect on inner medullary collecting ducts (4). This effect is not blocked by the V 2 receptor antagonist (4) but is blocked by the specific antagonist A-779 (5,6) and losartan (7). Ang-(1-7) may play a role during dehydration and hemorrhage in rats (8).…”