Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, USA.
Department of Medicine, University of Minnesota, Minneapolis, MN, USA.
Exp Physiol. 2020 May;105(5):886-892. doi: 10.1113/EP088452. Epub 2020 Apr 16.
What is the central question of this study? What is the role of β -adrenergic receptor (β AR) vasodilatation in older postmenopausal women as compared to premenopausal women and the role of nitric oxide (NO) in β AR-mediated vasodilatation in both groups of women? What is the main finding and its importance? β AR responsiveness is blunted in postmenopausal women compared to young premenopausal women. Additionally, NO may contribute to β AR-mediated vasodilatation in young premenopausal women.
β -Adrenergic receptor (β AR)-mediated vasodilatation, which is partially dependent on nitric oxide (NO) formation, is blunted in men at risk for developing hypertension. However, the role of β AR vasodilatation in hypertension pathophysiology in ageing postmenopausal women is unclear. Therefore, the goals of this study were to determine if forearm vasodilatation to the selective β AR agonist terbutaline is blunted in older postmenopausal women (59 ± 4 years) compared to young premenopausal women (27 ± 3 years) and to assess NO contribution to β AR-mediated vasodilatation in both groups of women. Forearm blood flow (FBF) and forearm vascular conductance (FVC) were measured using venous occlusion plethysmography at baseline and during intra-arterial infusions of terbutaline at 0.1-2.0 µg (100 ml tissue) min with and without the NO synthase inhibitor l-N -monomethylarginine (l-NMMA). Mean arterial pressure was significantly greater in postmenopausal women than in young women at baseline (P = 0.01). Baseline FBF and FVC did not differ between young and postmenopausal women (P > 0.05) and rose significantly within each group during terbutaline infusion (P < 0.05). There were significant group × dose interactions for FBF (P = 0.01) and FVC (P = 0.001), indicating vasodilator responses were lower in postmenopausal women. In young women, FVC response to the highest dose of terbutaline tended to be lower with l-NMMA co-infusion vs. without l-NMMA (P = 0.05). There were no significant decreases in FBF or FVC responses to terbutaline in postmenopausal women with l-NMMA co-infusion (P > 0.05 for all). These data suggest that β AR responsiveness is blunted in postmenopausal women compared to young premenopausal women, and that NO may contribute to β AR-mediated vasodilatation in young premenopausal women.
这项研究的核心问题是什么？与年轻的绝经前女性相比，β-肾上腺素能受体（β AR）血管舒张在老年绝经后女性中的作用是什么，以及在这两组女性中，一氧化氮（NO）在β AR 介导的血管舒张中的作用是什么？主要发现及其重要性是什么？与年轻的绝经前女性相比，绝经后女性的β AR 反应性降低。此外，NO 可能有助于年轻绝经前女性的β AR 介导的血管舒张。
β-肾上腺素能受体（β AR）介导的血管舒张部分依赖于一氧化氮（NO）的形成，在有发生高血压风险的男性中减弱。然而，β AR 血管舒张在老年绝经后妇女的高血压病理生理学中的作用尚不清楚。因此，本研究的目的是确定与年轻的绝经前女性（27 ± 3 岁）相比，老年绝经后女性（59 ± 4 岁）的选择性β AR 激动剂特布他林引起的前臂血管舒张是否减弱，并评估 NO 对两组女性的β AR 介导的血管舒张的贡献。使用静脉闭塞容积描记法在基线和经皮内动脉输注特布他林 0.1-2.0μg（100ml 组织）min 时测量前臂血流量（FBF）和前臂血管传导率（FVC），并在存在和不存在一氧化氮合酶抑制剂 l-N-单甲基精氨酸（l-NMMA）时。绝经后妇女的平均动脉压明显高于年轻妇女（P=0.01）。年轻女性和绝经后女性的基础 FBF 和 FVC 无差异（P＞0.05），并且在特布他林输注期间在每个组中均显着升高（P＜0.05）。FBF（P=0.01）和 FVC（P=0.001）存在显著的组×剂量相互作用，表明绝经后妇女的血管舒张反应较低。在年轻女性中，特布他林最高剂量时的 FVC 反应在与 l-NMMA 共同输注时趋于较低（P=0.05）。在与 l-NMMA 共同输注时，绝经后妇女特布他林的 FBF 或 FVC 反应均无明显降低（P＞0.05）。
这些数据表明，与年轻的绝经前女性相比，绝经后女性的β AR 反应性降低，并且 NO 可能有助于年轻绝经前女性的β AR 介导的血管舒张。
