Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX 75231, USA.
Hypertension. 2012 Jan;59(1):98-104. doi: 10.1161/HYPERTENSIONAHA.111.176560. Epub 2011 Nov 21.
Previous human studies have shown that large-artery stiffness contributes to an age-related decrease in cardiovagal baroreflex sensitivity. Whether this is also true with sympathetic baroreflex sensitivity is unknown. We tested the hypothesis that sympathetic baroreflex sensitivity is associated with the stiffness of baroreceptor segments (the carotid artery and the aorta) in elderly individuals and that sex affects this relationship. Sympathetic baroreflex sensitivity was assessed from the spontaneous changes in beat-by-beat diastolic pressure and corresponding muscle sympathetic nerve activity (microneurography) during supine rest in 30 men (mean±SEM: 69±1 years) and 31 women (68±1 years). Carotid artery stiffness (B-mode ultrasonography) and aortic stiffness (MRI) were also determined. We found that elderly women had lower sympathetic baroreflex sensitivity than elderly men (-2.33±0.25 versus -3.32±0.25 bursts · 100 beats(-1) · mm Hg(-1); P=0.007). β-Stiffness indices of the carotid artery and the aorta were greater in elderly women than in men (6.68±0.48 versus 5.10±0.50 and 4.03±0.47 versus 2.68±0.42; both P<0.050). Sympathetic baroreflex sensitivity was inversely correlated with carotid artery stiffness in both men and women (r=0.49 and 0.50; both P<0.05), whereas this relation was shifted in parallel upward (toward a reduced sensitivity) in women with no changes in the slope (0.26 versus 0.24 arbitrary units). Sympathetic baroreflex sensitivity and aortic stiffness showed similar trends. Thus, barosensory artery stiffness seems to be one independent determinant of sympathetic baroreflex sensitivity in elderly men and women. The lower sympathetic baroreflex sensitivity in elderly women may predispose them to an increased prevalence of hypertension.
先前的人体研究表明，大动脉僵硬与心血管迷走神经反射敏感性随年龄下降有关。交感神经反射敏感性是否也如此尚不清楚。我们检验了这样一个假设，即交感神经反射敏感性与老年个体的压力感受器节段（颈动脉和主动脉）的僵硬程度有关，而性别会影响这种关系。通过在仰卧休息时，从逐拍舒张期血压和相应的肌肉交感神经活动（微神经记录法）的自发变化中评估交感神经反射敏感性。在 30 名男性（平均±SEM：69±1 岁）和 31 名女性（68±1 岁）中进行了评估。还确定了颈动脉僵硬（B 型超声检查）和主动脉僵硬（MRI）。我们发现，老年女性的交感神经反射敏感性低于老年男性（-2.33±0.25 比-3.32±0.25 爆发·100 次·mmHg(-1)·1(-1)；P=0.007）。老年女性的颈动脉和主动脉的β-僵硬指数大于男性（6.68±0.48 比 5.10±0.50 和 4.03±0.47 比 2.68±0.42；均 P<0.050）。在男性和女性中，交感神经反射敏感性与颈动脉僵硬呈负相关（r=0.49 和 0.50；均 P<0.05），而这种关系在女性中呈平行向上移动（向敏感性降低方向移动），斜率没有变化（0.26 比 0.24 个任意单位）。交感神经反射敏感性与主动脉僵硬呈相似趋势。因此，压力感受动脉僵硬似乎是老年男性和女性交感神经反射敏感性的一个独立决定因素。老年女性较低的交感神经反射敏感性可能使她们更容易患上高血压。
