Depressive Effects of Chronic Intermittent Hypobaric Hypoxia on Renal Vascular Hypertension through Enhancing Baroreflex

Abstract

Baroreflex function plays a critical role in the maintenance of cardiovascular homeostasis and is impaired in different types of hypertension in both human and animals. Chronic intermittent hypobaric hypoxia (CIHH) facilitates baroreflex in anesthetized rats. The aim of present study was to investigate the effect of CIHH on arterial blood pressure (ABP) and baroreflex function in renal vascular hypertension (RVH) rats. Adult male Sprague-Dawley rats were randomly divided into four groups: Sham-operated (SHAM), RVH, CIHH treatment (CIHH), and RVH plus CIHH (RVH+CIHH) groups. RVH was induced by 2-kidney-1-clip method. CIHH rats experienced 28-day (6 h per day) hypobaric hypoxia simulating 5,000 m altitude in hypobaric chamber. Renal sympathetic nerve activity (RSNA), ABP and heart rate (HR) were recorded. Baroreflex was elicited by intravenous infusion of phenylephrine (PE, 25 μg/kg) and sodium nitroprusside (SNP, 10 μg/KG), respectively. Baroreflex curves were plotted by using RSNA or HR v.s. mean arterial pressure (MAP). The systolic ABP measured by tail-cuff method was significantly higher in RVH rats compared with SHAM rats. Furthermore, RSNA-MAP baroreflex curves were shifted to the right and upward with a decrease in baroreflex gain (Gmax) in RVH rats. CIHH treatment significantly decreased systolic ABP in RVH rats to the level in SHAM rats and shifted RSNA-MAP baroreflex curves to the left and downward with a normalized Gmax. These data suggest that CIHH treatment produces an anti-hypertensive effect in RVH rats, likely due to facilitating baroreflex function. Thus, CIHH represents a novel potential therapeutics to treat hypertension.

Chronic Intermittent Hypobaric Hypoxia Ameliorates Renal Vascular Hypertension Through Up-regulating NOS in Nucleus Tractus Solitarii

“…Our previous studies have shown that CIHH facilitates the baroreceptor reflex and enhances the stable reduction of fluctuations in BP [7]. Recently, we confirmed that CIHH enhances baroreflex sympathetic inhibition, facilitates the baroreceptor reflex, and antagonizes the impaired baroreceptor reflex function in renal hypertensive rats [6]. The present study further investigated the central mechanism of the CIHH anti-hypertension effect and focused on the NTS in RVH rats.…”

“…It has been reported that chronic intermittent hypobaric hypoxia (CIHH) decreases arterial blood pressure (ABP) in patients with essential hypertension and in spontaneously hypertensive rats [4,5]. Our previous study demonstrated that CIHH decreases ABP in rats with renovascular hypertension (RVH) [6].…”

“…shown that the baroreflex is impaired in a variety of animal models of hypertension (such as spontaneously hypertensive rats, RVH, and metabolic syndrome hypertension) and in human hypertension [5]. Our previous study has shown that CIHH facilitates baroreflex function, a mechanism of the anti-hypertensive effect of CIHH in RVH rats [6,7]. However, the molecular and cellular mechanisms underlying the CIHH-induced facilitation of the baroreflex have not been elucidated.…”

Chronic intermittent hypobaric hypoxia improves markers of iron metabolism in a model of dietary-induced obesity

“…Accumulating evidence has demonstrated the benefits of chronic intermittent hypobaric hypoxia (CIHH) on multiple organs of the body such as heart, brain, liver, and kidney [ 15 – 18 ], including regulating immune system, anti-collagen-induced arthritis [ 19 ], antihypertensive activity [ 15 ], and improving dyslipidemia and glucose tolerance in type 2 diabetes [ 16 ] . Recently, it was reported that CIHH had an anti- aplastic anemia eect through improving the adhesiveness and stress of mesenchymal stem cells [ 20 ], and a modulating effect on brain iron homeostasis in rats [ 18 ] .…”

Oxidative Stress and the Kidney in the Space Environment

“…A rat model investigated the effect of chronic intermittent hypobaric hypoxia (CIHH) on arterial blood pressure (ABP) and baroreflex function in renal vascular hypertension (RVH). According to the model, CIHH resulted in the recession of renovascular hypertension through the facilitation of a baroreflex control [ 83 ]. Moreover, the beneficial impact of radiation was shown in nephrectomized rats that achieved better blood pressure control and proteinuria levels, compared to their controls [ 84 ].…”