Bruno R M, Cogo A, Ghiadoni L, Duo E, Pomidori L, Sharma R, Thapa G B, Basnyat B, Bartesaghi M, Picano E, Sicari R, Taddei S, Pratali L
Institute of Clinical Physiology - CNR, Pisa, Italy; Department of Clinical and Experimental Medicine, University of Pisa, Italy.
Biomedical Sport Studies Center, University of Ferrara, Italy.
Atherosclerosis. 2014 Sep;236(1):47-53. doi: 10.1016/j.atherosclerosis.2014.06.017. Epub 2014 Jun 25.
Residents of the Himalayan valleys uniquely adapted to their hypoxic environment in terms of pulmonary vasculature, but their systemic vascular function is still largely unexplored. The aim of the study was to investigate vascular function and structure in rural Sherpa population, permanently living at high altitude in Nepal (HA), in comparison with control Caucasian subjects (C) living at sea level.
95 HA and 64 C were enrolled. Cardiac ultrasound, flow-mediated dilation (FMD) of the brachial artery, carotid geometry and stiffness, and aortic pulse wave velocity (PWV) were performed. The same protocol was repeated in 11 HA with reduced FMD, after 1-h 100% O2 administration. HA presented lower FMD (5.18 ± 3.10 vs. 6.44 ± 2.91%, p = 0.02) and hyperemic velocity than C (0.61 ± 0.24 vs. 0.75 ± 0.28 m/s, p = 0.008), while systolic pulmonary pressure was higher (29.4 ± 5.5 vs. 23.6 ± 4.8 mmHg, p < 0.0001). In multiple regression analysis performed in HA, hyperemic velocity remained an independent predictor of FMD, after adjustment for baseline brachial artery diameter, room temperature and pulse pressure, explaining 8.7% of its variance. On the contrary, in C brachial artery diameter remained the only independent predictor of FMD, after adjustment for confounders. HA presented also lower carotid IMT than C (0.509 ± 0.121 vs. 0.576 ± 0.122 mm, p < 0.0001), higher diameter (6.98 ± 1.07 vs. 6.81 ± 0.85 mm, p = 0.004 adjusted for body surface area) and circumferential wall stress (67.6 ± 13.1 vs. 56.4 ± 16.0 kPa, p < 0.0001), while PWV was similar. O2 administration did not modify vascular variables.
HA exhibit reduced NO-mediated dilation in the brachial artery, which is associated to reduced hyperemic response, indicating microcirculatory dysfunction. A peculiar carotid phenotype, characterized by reduced IMT and enlarged diameter, was also found.
喜马拉雅山谷的居民在肺血管方面对其低氧环境具有独特的适应性，但其全身血管功能仍 largely 未被探索。本研究的目的是调查长期生活在尼泊尔高海拔地区（HA）的夏尔巴农村人口的血管功能和结构，并与生活在海平面的对照高加索受试者（C）进行比较。
纳入了95名HA和64名C。进行了心脏超声、肱动脉血流介导的血管舒张（FMD）、颈动脉几何形状和僵硬度以及主动脉脉搏波速度（PWV）检查。在11名FMD降低的HA中，给予1小时100%氧气后重复相同方案。HA的FMD低于C（5.18±3.10%对6.44±2.91%，p = 0.02），充血速度也低于C（0.61±0.24对0.75±0.28 m/s，p = 0.008），而收缩期肺动脉压更高（29.4±5.5对23.6±4.8 mmHg，p < 0.0001）。在对HA进行的多元回归分析中，在调整了基线肱动脉直径、室温及脉压后，充血速度仍是FMD的独立预测因素，解释了其8.7%的方差。相反，在C中，调整混杂因素后，肱动脉直径仍是FMD的唯一独立预测因素。HA的颈动脉内膜中层厚度也低于C（0.509±0.121对0.576±0.122 mm，p < 0.0001），直径更大（6.98±1.07对6.81±0.85 mm，经体表面积调整后p = 0.004），圆周壁应力更高（67.6±13.1对56.4±16.0 kPa，p < 0.0001），而PWV相似。给予氧气并未改变血管变量。
HA的肱动脉中NO介导的血管舒张降低，这与充血反应降低相关，表明存在微循环功能障碍。还发现了一种独特的颈动脉表型，其特征为内膜中层厚度降低和直径增大。
