Coconut oil supplementation and physical exercise improves baroreflex sensitivity and oxidative stress in hypertensive rats.

The hypothesis that oral supplementation with virgin coconut oil (Cocos nucifera L.) and exercise training would improve impaired baroreflex sensitivity (BRS) and reduce oxidative stress in spontaneously hypertensive rats (SHR) was tested. Adult male SHR and Wistar Kyoto rats (WKY) were divided into 5 groups: WKY + saline (n = 8); SHR + saline (n = 8); SHR + coconut oil (2 mL·day(-1), n = 8); SHR + trained (n = 8); and SHR + trained + coconut oil (n = 8). Mean arterial pressure (MAP) was recorded and BRS was tested using phenylephrine (8 µg/kg, intravenous) and sodium nitroprusside (25 µg·kg(-1), intravenous). Oxidative stress was measured using dihydroethidium in heart and aorta. SHR + saline, SHR + coconut oil, and SHR + trained group showed higher MAP compared with WKY + saline (175 ± 6, 148 ± 6, 147 ± 7 vs. 113 ± 2 mm Hg; p < 0.05). SHR + coconut oil, SHR + trained group, and SHR + trained + coconut oil groups presented lower MAP compared with SHR + saline group (148 ± 6, 147 ± 7, 134 ± 8 vs. 175 ± 6 mm Hg; p < 0.05). Coconut oil combined with exercise training improved BRS in SHR compared with SHR + saline group (-2.47 ± 0.3 vs. -1.39 ± 0.09 beats·min(-1)·mm Hg(-1); p < 0.05). SHR + saline group showed higher superoxide levels when compared with WKY + saline (774 ± 31 vs. 634 ± 19 arbitrary units (AU), respectively; p < 0.05). SHR + trained + coconut oil group presented reduced oxidative stress compared with SHR + saline in heart (622 ± 16 vs. 774 ± 31 AU, p < 0.05). In aorta, coconut oil reduced oxidative stress in SHR compared with SHR + saline group (454 ± 33 vs. 689 ± 29 AU, p < 0.05). Oral supplementation with coconut oil combined with exercise training improved impaired BRS and reduced oxidative stress in SHR.

Quercetin improves baroreflex sensitivity in spontaneously hypertensive rats.

Quercetin is a well-known antioxidant. Here, we investigated the effects of treatment with quercetin on mean arterial pressure (MAP), heart rate (HR) and baroreflex sensitivity (BRS) in spontaneously hypertensive rats (SHR). SHR and their controls (WKY) were orally treated with quercetin (2, 10 or 25 mg/kg/day) or saline for seven days. On the 8th day, MAP and HR were recorded. BRS was tested using phenylephrine (8 mg/kg, i.v.) and sodium nitroprusside (25 mg/kg, i.v.). Oxidative stress was measured by tiobarbituric acid reactive species assay. The doses of 10 (n = 8) and 25 mg/kg (n = 8) were able to decrease the MAP in SHR (n = 9) (163 ± 4 and 156 ± 5 vs. 173 ± 6, respectively, p < 0.05) but not in WKY (117 ± 1 and 118 ± 2 vs. 113 ± 1, respectively, p < 0.05). The dose of 25 mg/kg/day increased the sensitivity of parasympathetic component of the baroreflex (−2.47 ± 0.31 vs. −1.25 ± 0.8 bpm/mmHg) and decreased serum oxidative stress in SHR (2.04 ± 0.17 vs. 3.22 ± 0.37 nmol/mL, n = 6). Our data suggest that treatment with quercetin reduces hypertension and improves BRS in SHR via reduction in oxidative stress.

Active intervals between sets of resistance exercises potentiate the magnitude of postexercise hypotension in elderly hypertensive women.

Active and passive intervals (AI, PI) between exercise series promote different hemodynamic responses; however, the impact of these intervals on the blood pressure response has not yet been investigated. The objective of this study was to compare the impact of AIs and PIs during resistance exercises with the magnitude of postexercise hypotension (PEH). Elderly hypertensive women (n = 21, 61.2 ± 2 years of age) completed 4 sessions for upper or lower limbs with AI or PI (3 sets, 15 repetitions, 60% load of 15 repetition maximum (RM), and an interval of 90 seconds between sets). Blood pressure was measured 10 minutes before and at 10, 20, 30, 40, and 50 minutes after the exercise sessions. The heart rate at the end of each AI was always significantly higher than that after the PI, but the perceived exertion as measured by the Perceived Exertion Scale (OMNI-RPE) was similar to that of PI exercise protocols. In the lower limb exercises, AI resulted in significantly and consistently higher PEH than in exercises with PI for both systolic (from 20 minutes postexercise) and diastolic (from 10 minutes postexercise) pressures. The upper limb exercises promoted much more discrete PEH in relation to the lower limb exercises, given that the AI promoted significantly higher PEH relative to the PI protocols, but only for systolic PEH and only from 30 minutes postexercise. This is the first time that AIs between sets in a session of resistance exercises have been shown to be a highly effective methodological strategy to increase PEH in elderly hypertensive women.