Korean J Physiol Pharmacol.  2018 Jul;22(4):447-456. 10.4196/kjpp.2018.22.4.447.

Angiotensin-(1-9) ameliorates pulmonary arterial hypertension via angiotensin type II receptor

• Cha SA
• Park BM
• Kim SH

• KMID: 2414269
• DOI: http://doi.org/10.4196/kjpp.2018.22.4.447

Abstract

Angiotensin-(1-9) [Ang-(1-9)], generated from Ang I by Ang II converting enzyme 2, has been reported to have protective effects on cardiac and vascular remodeling. However, there is no report about the effect of Ang-(1-9) on pulmonary hypertension. The aim of the present study is to investigate whether Ang-(1-9) improves pulmonary vascular remodeling in monocrotaline (MCT)-induced pulmonary hypertensive rats. Sprague-Dawley rats received Ang-(1-9) (576 µg/kg/day) or saline via osmotic mini-pumps for 3 weeks. Three days after implantation of osmotic mini-pumps, 50 mg/kg MCT or vehicle were subcutaneously injected. MCT caused increases in right ventricular weight and systolic pressure, which were reduced by co-administration of Ang-(1-9). Ang-(1-9) also attenuated endothelial damage and medial hypertrophy of pulmonary arterioles as well as pulmonary fibrosis induced by MCT. The protective effects of Ang-(1-9) against pulmonary hypertension were inhibited by Ang type 2 receptor (ATâ‚‚R) blocker, but not by Mas receptor blocker. Additionally, the levels of LDH and inflammatory cytokines, such as TNF-α, MCP-1, IL-1β, and IL-6, in plasma were lower in Ang-(1-9) co-treated MCT group than in vehicle-treated MCT group. Changes in expressions of apoptosis-related proteins such as Bax, Bcl-2, Caspase-3 and -9 in the lung tissue of MCT rats were attenuated by the treatment with Ang-(1-9). These results indicate that Ang-(1-9) improves MCT-induced pulmonary hypertension by decreasing apoptosis and inflammatory reaction via ATâ‚‚R.

Keyword

Angiotensin-(1-9); Angiotensin II type 2 receptor; Apoptosis; Pulmonary hypertension

MeSH Terms

Angiotensins*
Animals
Apoptosis
Arterioles
Blood Pressure
Caspase 3
Cytokines
Hypertension*
Hypertension, Pulmonary
Hypertrophy
Interleukin-6
Lung
Monocrotaline
Plasma
Pulmonary Fibrosis
Rats
Rats, Sprague-Dawley
Receptor, Angiotensin, Type 2
Vascular Remodeling
Angiotensins
Caspase 3
Cytokines
Interleukin-6
Monocrotaline
Receptor, Angiotensin, Type 2

Figure

• 

  Fig. 1 Effects of Ang-(1-9) on ventricular pressure and weight, and plasma hormone levels in MCT-treated rats.Changes in RVSP (A), RV/LV+septum (B), ANP in ventricular tissue (C), and PRC (D) with and without Ang-(1-9) in MCT-treated rats. RVSP, right ventricular systolic pressure; RV/LV+septum, the ratio of free wall of right ventricular weight to left ventricular weight+septal weight; PRC, plasma renin concentration; MCT, monocrotaline; LV, RV, left and right ventricle, respectively; PD, PD123,319. Values are expressed as mean±SEM of 8 rats per groups. *vs. sham rats, p<0.05, **p<0.01; #vs. MCT rats, p<0.05; $vs. Ang-(1-9), p<0.05.

• 

  Fig. 2 Effects of Ang-(1-9) on MCT-induced pulmonary arterial intimal proliferation.(A) Representative H&E staining (bar=100 µM) and immunohistochemical staining for α-SMA and vWF (bar=50 µM) in lung tissues of MCT rats with or without Ang-(1-9). (B) Quantification of the medial thickness of pulmonary vessels <50 µm and 50–100 µm in external diameter. Values are expressed as mean±SEM of approximately 30 arterioles of 5 rats per groups. α-SMA, α-smooth muscle actin; vWF, von Willebrand Factor. *vs. sham rats, p<0.05; #vs. MCT rats, p<0.05.

• 

  Fig. 3 Plasma cytokine levels in MCT-treated rats.Plasma levels of ANP (A), LDH (B), MCP-1 (C), IL-1β (D), IL-6 (E) and TNF-α (F) with or without Ang-(1-9). Values are expressed as mean±SEM of 8 rats per groups. *vs. sham rats, p<0.05, **p<0.01; #vs. MCT rats, p < 0.05; $vs. Ang-(1-9), p<0.05.

• 

  Fig. 4 Effects of Ang-(1-9) on MCT-induced pulmonary fibrosis.Immunohistological analysis of pulmonary fibrosis using Sirius-red (Aa), Trichrome masson (Ab) staining (bar=100 µM) and quantification by modified ashcroft scoring system (B) with or without Ang-(1-9). Values are expressed as mean±SEM of 8 rats per groups. **vs. sham rats, p<0.01; #vs. MCT rats, p<0.05; $vs. Ang-(1-9), p<0.05.

• 

  Fig. 5 Effects of Ang-(1-9) on apoptotic-related protein expressions in lung tissues of MCT rats.Representative western blotting of Bax, Bcl-2, Caspase-3, and Caspase-9 protein expressions in lung tissues of MCT rats with or without Ang-(1-9) (A) and quantification of protein expressions compared to GAPDH (B). Values are expressed as mean±SEM of 8 rats per groups. V, vehicle; PD, PD123,319; A, A779. *vs. sham rats, p<0.05, **p<0.01; #vs. MCT rats, p<0.05.

• 

  Fig. 6 Effects of Ang-(1-9) on angiotensin-related protein expressions in lung tissues of MCT rats.Representative western blotting of angiotensin type 1 receptor (AT1R), AT2R, Mas receptor (Mas R), and angiotensin converting enzyme (ACE) protein expressions in lung tissues of MCT rats with or without Ang-(1-9) (A) and quantification of protein expressions compared to GAPDH (B). Values are expressed as mean±SEM of 8 rats per groups. V, vehicle; PD, PD123,319; A, A779. *vs. sham rats, p<0.05, **p<0.01; #vs. MCT rats, p<0.05.

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