Long-term exposure to high-altitude hypoxic environments reduces blood pressure by inhibiting the renin-angiotensin system in rats

Figures

• 

  FIGURE 1. Effect of high-altitude hypoxic conditions on blood pressure in spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats. (A) Systolic blood pressure (SBP). (B) Diastolic blood pressure (DBP). (C) Mean blood pressure (MBP). (D) Heart rate (HR). Data are presented as the median (interquartile range) (n = 6). Note: WKY-C, SHR-C, WKY-H, and SHR-H refer to the WKY control group, SHR control group, WKY high-altitude hypoxia group, and SHR high-altitude hypoxia group, respectively. *P < 0.05 (vs. WKY-C), #P < 0.05 (vs. SHR-C), and △P < 0.05 (vs. WKY-H).

• 

  FIGURE 2. Effect of high-altitude hypoxic conditions on cardiac output (CO), ejection fraction (EF), fractional shortening (FS), stroke volume (SV), left ventricular end-diastolic diameter (LVDd), left ventricular internal dimension systole (LVSd), left ventricular end-systolic anterior wall thickness (LVAMs), and left ventricular end-diastolic anterior wall thickness (LVAMd) in spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats. (A) Echocardiography. (B) Left ventricular functional indices. Data are presented as the median (interquartile range) (n = 4). Note: WKY-C, SHR-C, WKY-H, and SHR-H refer to the WKY control group, SHR control group, WKY high-altitude hypoxia group, and SHR high-altitude hypoxia group, respectively. *P < 0.05 (vs. WKY-C), #P < 0.05 (vs. SHR-C), and △P < 0.05 (vs. WKY-H).

• 

  FIGURE 3. Effect of high-altitude hypoxic conditions on mean pulmonary arterial pressure (mPAP), right ventricular systolic pressure (RVSP), and right ventricular end-diastolic pressure (RVEDP) in Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). (A) mPAP, (B) RVSP, and (C) RVEDP. Data are presented as the median (interquartile range) (n = 6). Note: WKY-C, SHR-C, WKY-H, and SHR-H refer to the WKY control group, SHR control group, WKY high-altitude hypoxia group, and SHR high-altitude hypoxia group, respectively. *P < 0.05 (vs. WKY-C) and #P < 0.05 (vs. SHR-C).

• 

  FIGURE 4. Changes in white blood cell, red blood cell, haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, and platelet levels in Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) after exposure to high-altitude hypoxic conditions. Data are presented as the median (interquartile range) (n = 6). Note: WKY-C, SHR-C, WKY-H, and SHR-H refer to the WKY control group, SHR control group, WKY high-altitude hypoxia group, and SHR high-altitude hypoxia group, respectively. *P < 0.05 (vs. WKY-C), #P < 0.05 (vs. SHR-C), and △P < 0.05 (vs. WKY-H).

• 

  FIGURE 5. Changes in alanine aminotransferase, aspartate aminotransferase, creatinine, glucose, urea, low-density lipoprotein cholesterol, total cholesterol, and triglyceride levels in Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) after exposure to high-altitude hypoxic conditions. Data are presented as the median (interquartile range) (n = 6). Note: WKY-C, SHR-C, WKY-H, and SHR-H refer to the WKY control group, SHR control group, WKY high-altitude hypoxia group, and SHR high-altitude hypoxia group, respectively. *P < 0.05 (vs. WKY-C), #P < 0.05 (vs. SHR-C), and △P < 0.05 (vs. WKY-H).

• 

  FIGURE 6. Effect of high-altitude hypoxic conditions on heart, liver, lung, and kidney tissues in spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats. Haematoxylin and eosin staining. Note: WKY-C, SHR-C, WKY-H, and SHR-H refer to the WKY control group, SHR control group, WKY high-altitude hypoxia group, and SHR high-altitude hypoxia group, respectively.

• 

  FIGURE 7. Effect of high-altitude hypoxic conditions on abdominal aortic morphology, collagen, and elastic fibres in spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats. (A) Haematoxylin and eosin staining for morphology. (B) Masson’s staining for collagen. (C) Weigert’s staining for elastic fibres. (D) Abdominal aortic medial thickness. (E) Collagen fibre area. (F) Elastic fibre area. Data are presented as the median (interquartile range) (n = 5). Note: WKY-C, SHR-C, WKY-H, and SHR-H refer to the WKY control group, SHR control group, WKY high-altitude hypoxia group, and SHR high-altitude hypoxia group, respectively. *P < 0.05 (vs. WKY-C) and #P < 0.05 (vs. SHR-C).

• 

  FIGURE 8. Effect of high-altitude hypoxic conditions on angiotensin Ⅰ (Ang I), angiotensin-converting enzyme (ACE), angiotensin II (Ang II), angiotensin II type I receptor (AT1R), angiotensin-converting enzyme 2 (ACE 2), angiotensin 1–7 (Ang [1–7]), and Mas receptor (MasR) expression in Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Data are presented as the median (interquartile range) (n = 6). Note: WKY-C, SHR-C, WKY-H, and SHR-H refer to the WKY control group, SHR control group, WKY high-altitude hypoxia group, and SHR high-altitude hypoxia group, respectively. *P < 0.05 (vs. WKY-C) and #P < 0.05 (vs. SHR-C).