Oxidative stress plays a role in maintaining high arterial blood pressure and contributes to the vascular changes that lead to hypertension. Consumption of polyphenol-rich foods has demonstrated their beneficial role in the prevention and treatment of hypertension. Curcumin (CUR), a phenolic compound present in the rhizomes of turmeric, possesses cardiovascular protective, anti-inflammatory and antioxidant properties. The present study was designed to investigate the protective effect of CUR on 2kidney-1clip (2K-1C)-induced hypertension, endothelial dysfunction, vascular remodeling and oxidative stress in male Sprague-Dawley rats. Sham operated or 2K-1C rats were treated with CUR at a dose of 50 or 100 mg/kg/day (or vehicle). After 6 weeks of treatment, CUR ameliorated hemodynamic performance in 2K-1C hypertensive rats (P< 0.05), by reducing blood pressure, increasing hindlimb blood flow and decreasing hindlimb vascular resistance. Hemodynamic restoration was associated with a reduction in plasma angiotensin converting enzyme level. Endothelium-dependent vasorelaxation, in response to acetylcholine, of aortic rings isolated from 2K-1C hypertensive rats-treated with CUR was significantly increased (P< 0.05). CUR also attenuated hypertension-induced oxidative stress and vascular structural modifications. These effects were associated with elevated plasma nitrate/nitrite, upregulated eNOS expression, downregulated p47phox NADPH oxidase and decreased superoxide production in the vascular tissues. The overall findings of this study suggest the mechanisms responsible for the antihypertensive action of CUR in 2K-1C hypertension-induced endothelial dysfunction and vascular remodeling involve the improvement NO bioavailability and a reduction in oxidative stress.
In recent years, a number of studies have investigated complementary medical approaches to the treatment of hypertension using dietary supplements. Rice bran protein hydrolysates extracted from rice is a rich source of bioactive peptides. The present study aimed to investigate the vasorelaxation and antihypertensive effects of peptides-derived from rice bran protein hydrolysates (RBP) in a rat model of two kidney-one clip (2K-1C) renovascular hypertension. 2K-1C hypertension was induced in male Sprague-Dawley rats by placing a silver clip around the left renal artery, whereas sham-operated rats were served as controls. 2K-1C and sham-operated rats were intragastrically administered with RBP (50 mg·kg−1 or 100 mg·kg−1) or distilled water continuously for six weeks. We observed that RBP augmented endothelium-dependent vasorelaxation in all animals. Administration of RBP to 2K-1C rats significantly reduced blood pressure and decreased peripheral vascular resistance compared to the sham operated controls (p < 0.05). Restoration of normal endothelial function and blood pressure was associated with reduced plasma angiotensin converting enzyme (ACE), decreased superoxide formation, reduced plasma malondialdehyde and increased plasma nitrate/nitrite (p < 0.05). Up-regulation of eNOS protein and down-regulation of p47phox protein were found in 2K-1C hypertensive rats-treated with RBP. Our results suggest that RBP possesses antihypertensive properties which are mainly due to the inhibition of ACE, and its vasodilatory and antioxidant activity.
Reactive oxygen species (ROS)-induced oxidative stress plays a major role in pathogenesis of hypertension. Antidesma thwaitesianum (local name: Mamao) is a tropical plant distributed in the tropical/subtropical areas of the world, including Thailand. Mamao pomace (MP), a by-product generated from Mamao fruits, contains large amounts of antioxidant polyphenolic compounds. The aim of this study was to investigate the antihypertensive and antioxidative effects of MP using hypertensive rats. For this purpose, male Sprague-Dawley rats were given Nω-nitro-l-arginine methyl ester (l-NAME), an inhibitor of endothelial nitric oxide synthase (eNOS), in drinking water (50 mg/kg) for three weeks. MP extract was orally administered daily at doses of 100 and 300 mg/kg. l-NAME administration induced marked increase in blood pressure, peripheral vascular resistance, and oxidative stress. MP treatment significantly prevented the increase in blood pressure, hindlimb blood flow and hindlimb vascular resistance of l-NAME treated hypertensive rats (p < 0.05). The antihypertensive effect of MP treatment was associated with suppression of superoxide production from carotid strips and also with an increase in eNOS protein expression and nitric oxide bioavailability. The present results provide evidence for the antihypertensive effect of MP and suggest that MP might be useful as a dietary supplement against hypertension.
Chest wall expansion determines lung volume and functional capacity. Factors determining chest wall expansion include respiratory muscle strength. Accordingly, there may be association among respiratory muscle strength, chest wall expansion, and functional capacity. Thusly, this cross-sectional study identified the relationship between respiratory muscle strength, chest wall expansion, and functional capacity. Seventy-six healthy male and female participants aged between 20 to 59 years exhibiting a body mass index of 18.5 to 22.9 kg/m 2 were enrolled. Inspiratory and expiratory muscle strength were evaluated via maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP), respectively. Chest wall expansion was measured through thoracic circumferences at three different levels; upper, middle, and lower levels with diaphragmatic movement also measured utilizing the circumference of the lower edge of the 10th rib. Functional capacity was evaluated through distance obtained from a 6-min walk test. Results showed that both MIP and MEP were significantly correlated with chest wall expansion at the middle (P= 0.005 and P= 0.006) and lower (P= 0.012 and P= 0.020) thoracic levels as well as diaphragmatic movement (both P< 0.001). Moreover, both MIP and MEP were significantly related amid the 6-min walk distance (P= 0.025 and P< 0.001). In conclusion, respiratory muscle strength is positively associated with chest wall expansion, diaphragmatic movement, and functional capacity in healthy participants.
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