Chronic Intermittent Hypobaric Hypoxia Decreases High Blood Pressure by Stabilizing the Vascular Renin-Angiotensin System in Spontaneously Hypertensive Rats

Figures

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  FIGURE 1. Effect of chronic intermittent hypobaric hypoxia (CIHH) on body weight and arterial blood pressure in spontaneously hypertensive rat (SHR). (A) Body weight; (B) systolic blood pressure (SBP); (C) diastolic blood pressure (DBP); (D) heart rate (HR). Data are expressed as mean ± SEM; SHR-CON: control SHR (n = 12); SHR-CIHH: SHR with CIHH (n = 12); WKY-CON: control WKY rats (n = 6); WKY-CIHH: WKY rats with CIHH (n = 6); *P < 0.05, **P < 0.01 vs. WKY-CON, #P < 0.05, ##P < 0.01 vs. SHR-CON (two-way ANOVA).

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  FIGURE 2. The duration of the depressor effect by chronic intermittent hypobaric hypoxia (CIHH) on SBP (A) and DBP (B) in spontaneously hypertensive rats (SHRs). (A) SBP: systolic blood pressure; (B) DBP: diastolic blood pressure. Data are expressed as mean ± SEM; SHR-CON: control SHR (n = 6); SHR-CIHH: SHR with CIHH (n = 6); CIHH5: 5 weeks of CIHH; Post 1–Post 5: 1–5 weeks after CIHH; *P < 0.05, **P < 0.01 vs. SHR-CON (t-test).

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  FIGURE 3. Effect of chronic intermittent hypobaric hypoxia (CIHH) on serum angiotensin II (Ang II), angiotensin 1–7 (Ang1–7), IL-6, TNFα, and IL-10 in spontaneously hypertensive rats (SHRs). Data are expressed as mean ± SEM; SHR-CON: control SHR (n = 14); SHR-CIHH: SHR with CIHH (n = 14); WKY-CON: control WKY rat (n = 6); WKY-CIHH: WKY rat with CIHH (n = 6); *P < 0.05, **P < 0.01 vs. WKY-CON ##P < 0.01 vs. SHR-CON (one-way ANOVA).

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  FIGURE 4. Effect of chronic intermittent hypobaric hypoxia (CIHH) on angiotensin II (Ang II), angiotensin 1–7 (Ang1–7), IL-6, TNF-α, and IL-10 in mesenteric arteries of spontaneously hypertensive rats (SHRs). Data are expressed as mean ± SEM; n = 5 for each group. SHR-CON: control SHR; SHR-CIHH: SHR with CIHH; WKY-CON: control WKY rats; WKY-CIHH: WKY rats with CIHH; *P < 0.05, **P < 0.01 vs. WKY-CON, #P < 0.05, ##P < 0.01 vs. SHR-CON (one-way ANOVA).

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  FIGURE 5. Effect of chronic intermittent hypobaric hypoxia (CIHH) on PE-induced, KCl-induced, and Ang II-induced contraction of the mesenteric arteries from spontaneously hypertensive rats (SHRs). Summarized data of mesenteric arteries in response to KCl (A) and PE (B). Representative contraction traces (C) and summarized data (D) of mesenteric arteries in response to different concentrations of Ang II. Data are expressed as mean ± SEM; SHR-CON: control SHR (n = 14); SHR-CIHH: SHR with CIHH (n = 12); WKY-CON: control WKY rats (n = 12); WKY-CIHH: WKY rats with CIHH (n = 12); **P < 0.01 vs. WKY-CON, #P < 0.05, ##P < 0.01 vs. SHR-CON [one-way ANOVA for (A,B), two-way ANOVA for (C)].

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  FIGURE 6. Effect of chronic intermittent hypobaric hypoxia (CIHH) on ACh-induced relaxation in the mesenteric arteries of spontaneously hypertensive rats (SHRs). Representative traces (A) and summarized data (B) of mesenteric arteries in response to different concentrations of ACh after precontracted with PE. Data are expressed as mean ± SEM; SHR-CON: control SHR (n = 16); SHR-CIHH: SHR with CIHH (n = 14); WKY-CON: control WKY rats (n = 12); WKY-CIHH: WKY rats with CIHH (n = 12). **P < 0.01 vs. WKY-CON, #P < 0.05, ##P < 0.01 vs. SHR-CON (two-way ANOVA).

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  FIGURE 7. Effect of chronic intermittent hypobaric hypoxia (CIHH) on Ang 1–7-induced relaxation in mesenteric artery of spontaneously hypertensive rat (SHR). Representative traces (A) and summarized data (B) of mesenteric arteries in response to different concentrations of Ang 1–7 after precontracted with PE. Data are expressed as mean ± SEM; SHR-CON: control SHR (n = 16); SHR-CIHH: SHR with CIHH (n = 14); WKY-CON: control WKY rats (n = 12); WKY-CIHH: WKY rats with CIHH (n = 12). *P < 0.05, **P < 0.01 vs. WKY-CON, ##P < 0.01 vs. SHR-CON (two-way ANOVA).

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  FIGURE 8. Effect of chronic intermittent hypobaric hypoxia (CIHH) on vascular structure and collagen volume in the mesenteric arteries of spontaneously hypertensive rats (SHRs). (A) Representative HE staining and summarized vessel diameter and vessel wall thickness data in the different groups: Scale bar 50 μm, magnification × 400, (B) representative and summarized Masson’s staining data: Scale bar 50 μm, magnification × 400, Data are expressed as mean ± SEM; n = 5 for each group. SHR-CON: control SHR; SHR-CIHH: SHR with CIHH; WKY-CON: control WKY rats; WKY-CIHH: WKY rats with CIHH. *P < 0.05 vs. WKY-CON, #P < 0.05, ##P < 0.01 vs. SHR-CON (one-way ANOVA).

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  FIGURE 9. Effect of chronic intermittent hypobaric hypoxia (CIHH) on the expression of ACE, ACE2, AT1, and Mas in the mesenteric arteries of spontaneously hypertensive rats (SHRs). Data are expressed as mean ± SEM; n = 6 for each group. SHR-CON: control SHR; SHR-CIHH: SHR with CIHH; WKY-CON: control WKY rats; WKY-CIHH: WKY rats with CIHH; *P < 0.05, **P < 0.01 vs. WKY-CON, #P < 0.05, ##P < 0.01 vs. SHR-CON (one-way ANOVA).