Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2195, USA.
Heart Rhythm. 2011 Mar;8(3):422-8. doi: 10.1016/j.hrthm.2010.11.009. Epub 2011 Jan 22.
Postural tachycardia syndrome (POTS) is a disorder characterized by excessive orthostatic tachycardia and significant functional disability. We previously reported that POTS patients have low blood volume and inappropriately low plasma renin activity (PRA) and aldosterone. In this study, we sought to more fully characterize the renin-angiotensin-aldosterone system (RAAS) to gain a better understanding of the pathophysiology of POTS.
The purpose of this study was to prospectively assess the plasma levels of angiotensin (Ang) peptides and their relationship to other RAAS components in patients with POTS compared with healthy controls.
Heart rate, PRA, Ang I, Ang II, Ang (1-7), and aldosterone were measured in POTS patients (n = 38) and healthy controls (n = 13) while they were consuming a sodium-controlled diet.
POTS patients had larger orthostatic increases in heart rate than did controls (52 ± 3 [mean ± SEM] bpm vs 27 ± 6 bpm, P = .001). Plasma Ang II was significantly higher in POTS patients (43 ± 3 pg/mL vs 28 ± 3 pg/mL, P = .006), whereas plasma Ang I and angiotensin 1-7 [Ang-(1-7)] were similar between groups. Despite the twofold increase of Ang II, POTS patients trended to lower PRA levels than did controls (0.9 ± 0.1 ng/mL/h vs 1.6 ± 0.5 ng/mL/h, P = .268) and lower aldosterone levels (4.6 ± 0.8 pg/mL vs 10.0 ± 3.0 pg/mL, P = .111). Estimated angiotensin-converting enzyme-2 (ACE2) activity was significantly lower in POTS patients than in controls (0.25 ± 0.02 vs 0.33 ± 0.03, P = .038).
Some patients with POTS have inappropriately high plasma Ang II levels, with low estimated ACE2 activity. We propose that these abnormalities in Ang regulation may play a key role in the pathophysiology of POTS in some patients.
体位性心动过速综合征（POTS）是一种以直立性心动过速和显著功能障碍为特征的疾病。我们之前报道过，POTS 患者存在血容量低和血浆肾素活性（PRA）及醛固酮水平不适当降低。在这项研究中，我们试图更全面地描述肾素-血管紧张素-醛固酮系统（RAAS），以更好地了解 POTS 的病理生理学。
本研究旨在前瞻性评估与健康对照组相比，POTS 患者的血管紧张素（Ang）肽的血浆水平及其与其他 RAAS 成分的关系。
在 POTS 患者（n=38）和健康对照组（n=13）摄入钠控制饮食时，测量心率、PRA、Ang I、Ang II、Ang（1-7）和醛固酮。
与对照组相比，POTS 患者的直立性心率增加更大（52±3bpm 与 27±6bpm，P=0.001）。POTS 患者的血浆 Ang II 明显升高（43±3pg/ml 与 28±3pg/ml，P=0.006），而两组的血浆 Ang I 和血管紧张素 1-7[Ang-（1-7）]相似。尽管 Ang II 增加了两倍，POTS 患者的 PRA 水平趋势低于对照组（0.9±0.1ng/ml/h 与 1.6±0.5ng/ml/h，P=0.268），且醛固酮水平较低（4.6±0.8pg/ml 与 10.0±3.0pg/ml，P=0.111）。POTS 患者的估计血管紧张素转换酶 2（ACE2）活性明显低于对照组（0.25±0.02 与 0.33±0.03，P=0.038）。
一些 POTS 患者的血浆 Ang II 水平异常升高，估计 ACE2 活性降低。我们提出，这些 Ang 调节异常可能在某些患者的 POTS 病理生理学中起关键作用。
