Exercise Training Lowers Arterial Blood Pressure Independently of Pannexin 1 in Men with Essential Hypertension.

INTRODUCTION: Regular exercise training reduces arterial blood pressure, but the underlying mechanisms are unclear. Here, we evaluated the potential involvement of pannexin 1, an ATP releasing channel, in the blood pressure-reducing effect of training. METHODS: Middle-age men, 13 normotensive and 14 nonmedicated stage 1 hypertensive, completed 8 wk of intensive aerobic cycle training. Before and after training, blood pressure and changes in leg vascular conductance, induced by femoral arterial infusion of tyramine (induces endogenous noradrenaline release), acetylcholine, or sodium nitroprusside, were measured during control conditions and after acute pannexin 1 inhibition by probenecid. A skeletal muscle biopsy was obtained from the thigh, pre- and posttraining. RESULTS: Exercise training reduced mean systolic and diastolic blood pressure by ~5 ( P = 0.013) and 5 mm Hg ( P < 0.001), respectively, in the hypertensive group only. The reduction in blood pressure was not related to changes in pannexin 1 function because mean arterial blood pressure and tyramine-induced vasoconstriction remain unaltered by pannexin 1 inhibition after training in both groups. After training, pannexin 1 inhibition enhanced leg vascular conductance in the normo- and hypertensive groups at baseline (41.5%, P = 0.0036, and 37.7%, P = 0.024, respectively) and in response to sodium nitroprusside infusion (275%, P = 0.038, and 188%, P = 0.038, respectively). Training did not alter the pannexin 1 protein expression in skeletal muscle. Training enhanced the vasodilator response to acetylcholine infusion and increased the expression of microvascular function-relevant proteins. CONCLUSIONS: The exercise training-induced lowering of arterial blood pressure in nonmedicated hypertensive men does not involve an altered function of pannexin 1.

High-Intensity Interval Training Decreases Muscle Sympathetic Nerve Activity in Men With Essential Hypertension and in Normotensive Controls.

Exercise training is a cornerstone in reducing blood pressure (BP) and muscle sympathetic nerve activity (MSNA) in individuals with essential hypertension. High-intensity interval training (HIIT) has been shown to be a time efficient alternative to classical continuous training in lowering BP in essential hypertension, but the effect of HIIT on MSNA levels has never been investigated. Leg MSNA responsiveness to 6 weeks of HIIT was examined in 14 hypertensive men (HYP; age: 62 ± 7 years, night time BP: 136 ± 12/83 ± 8 mmHg, BMI: 28 ± 3 kg/m2), and 10 age-matched normotensive controls (NORM; age: 60 ± 8 years, night time BP: 116 ± 2/68 ± 4 mmHg and BMI: 27 ± 3 kg/m2). Before training, MSNA levels were not different between HYP and NORM (burst frequency (BF): 41.0 ± 10.3 vs. 33.6 ± 10.6 bursts/min and burst incidence (BI): 67.5 ± 19.7 vs. 64.2 ± 17.0 bursts/100 heart beats, respectively). BF decreased (P < 0.05) with training by 13 and 5% in HYP and NORM, respectively, whereas BI decreased by 7% in NORM only, with no difference between groups. Training lowered (P < 0.05) night-time mean arterial- and diastolic BP in HYP only (100 ± 8 vs. 97 ± 5, and 82 ± 6 vs. 79 ± 5 mmHg, respectively). The change in HYP was greater (P < 0.05) compared to NORM. Training reduced (P < 0.05) body mass, visceral fat mass, and fat percentage similarly within- and between groups, with no change in fat free mass. Training increased (P < 0.05) V̇O2-max in NORM only. Six weeks of HIIT lowered resting MSNA levels in age-matched hyper- and normotensive men, which was paralleled by a significant reduction in BP in the hypertensive men.