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

FIGURE 1. A schematic representation of the experimental protocol. In 2K1C, DOCA‐salt‐treated and corresponding sham rats, following a 1.5 h stabilization period, an arterial blood sample was withdrawn. After intra‐renal infusion of saline, two urine samples were collected, each of 20 min, which was then followed by the withdrawal of a second blood sample. This was then followed by a 50‐min equilibration period during which Ang (1–7) was infused into the kidney instead of saline. Two further urine samples were collected, each of 20 min. Then, a third blood sample was withdrawn. P, plasma sample; C, clearance (urine sample)

FIGURE 2. Baseline MAP during the intrarenal infusion of saline and Ang (1–7). (a, b) Box and whiskers plots for each group, where each point represents MAP obtained from a single rat. MAP was not altered during the intrarenal infusion of Ang (1–7) compared to the intrarenal infusion of saline into the left kidney in any of the groups of 2K1C (sham, n = 7; NCK, n = 7; CK, n = 8) and DOCA (sham, n = 6; DOCA‐salt, n = 7) models. MAP remained relatively stable during the intrarenal infusion of Ang (1–7) compared to baseline in all groups of 2K1C and DOCA models. #P < 0.05 CK‐2K1C or DOCA‐salt versus sham 2K1C or sham DOCA, respectively; †P < 0.05 NCK‐2K1C versus Sham 2K1C. 2K1C; two‐kidney one‐clip; Ang (1–7), angiotensin (1–7); CK, clipped kidney; DOCA, deoxycorticosterone acetate; MAP, mean arterial blood pressure; NCK, non‐clipped kidney

FIGURE 3. The effect of intrarenal Ang (1–7) on kidney function in 2K1C rats. Each panel shows box and whisker plot of each renal functional parameter, where each point represents kidney function obtained from a single rat. Figure shows UV (a), UNaV (b), FENa (c) and GFR (d) obtained from sham 2K1C rats (n = 7), from the non‐clipped kidney (n = 7) and from the clipped kidney (n = 8) of 2K1C rats. *P < 0.05 Ang (1–7) versus saline, #P < 0.05 CK‐2K1C versus NCK‐2K1C or Sham 2K1C, †P < 0.05 NCK‐2K1C versus sham 2K1C. 2K1C; two‐kidney one‐clip; CK, clipped kidney; FENa, fractional sodium excretion; GFR, glomerular filtration rate; NCK, non‐clipped kidney; UNaV, absolute sodium excretion; UV, urine flow rate

FIGURE 4. The effect of intrarenal Ang (1–7) on kidney function in sham DOCA and DOCA‐salt‐treated rats. Each panel shows box and whisker plot of each renal functional parameter, where each point represents renal excretory parameter obtained from a single rat. Figure shows UV (a), UNaV (b), FENa (c) and GFR (d) obtained from sham DOCA rats (n = 6) and DOCA‐salt‐treated rats (n = 7) during the intra‐renal infusion of Ang (1–7) and saline. *P < 0.05 Ang (1–7) versus saline, #P < 0.05 DOCA‐salt versus sham DOCA. DOCA, deoxycorticosterone acetate; FENa, fractional sodium excretion; GFR, glomerular filtration rate; UNaV, absolute sodium excretion; UV, urine flow rate

FIGURE 5. Tissue concentration of Ang II and Ang (1–7). (a, b) Concentration of Ang II and Ang (1–7) in the kidneys of sham 2K1C (n = 5) and 2K1C rats (n = 5). (c, d) Concentration of Ang II (sham DOCA, n = 4; DOCA‐salt, n = 4) and Ang (1–7) (sham DOCA, n = 5; DOCA‐salt, n = 5) in the kidneys of sham DOCA and DOCA‐salt‐treated rats. (a, b) *P < 0.05 2K1C versus sham 2K1C; (c, d) *P < 0.05 DOCA‐salt versus sham DOCA. 2K1C; two‐kidney one‐clip; Ang II, angiotensin II; Ang (1–7), angiotensin 1–7; CK, clipped kidney; DOCA, deoxycorticosterone acetate; NCK, non‐clipped kidney

FIGURE 6. Protein expression of AT1 receptor in the cortex and medulla of 2K1C and DOCA rats. (a, c) Representative western blots with a band around 52 kDa marking the protein expression of AT1R in the cortex and medulla of the sham 2K1C (n = 4), NCK‐2K1C (n = 5) and CK‐2K1C rats (n = 5). (b) Relative AT1R density (normalised to Ponceau S loading control) in the cortex and medulla of sham 2K1C and 2K1C groups. (d) Relative AT1R density in the cortex and medulla of DOCA‐salt‐treated (n = 4) and sham DOCA (n = 5) rats. *P < 0.05 versus sham in 2K1C or DOCA groups. 2K1C; two‐kidney one‐clip; AT1R, angiotensin II type 1 receptor; CK, clipped kidney; DOCA, deoxycorticosterone acetate; NCK, non‐clipped kidney

FIGURE 7. Protein expression of Mas receptor in the renal cortex and medulla of 2K1C and DOCA rats. (a, c) Representative western blots with a band around 45 kDa marking the protein expression of Mas receptor in the cortex and medulla of the sham 2K1C (n = 4) and NCK‐2K1C (n = 4) rats. (b) Relative Mas receptor density (normalised to Ponceau S loading control) in the cortex and medulla of sham 2K1C and NCK‐2K1C groups. (d) Relative Mas receptor density in the cortex and medulla of DOCA‐salt‐treated (n = 4) and sham DOCA (n = 5) rats. *P < 0.05 DOCA‐salt versus sham DOCA. 2K1C; two‐kidney one‐clip; DOCA, deoxycorticosterone acetate; NCK, non‐clipped kidney