BLUNTED BAROREFLEX WITH AGE--ROLE OF CAROTID STIFFNESS

心血管系统自主神经调节的改变牵涉到 随着年龄的增长，心血管疾病的发病率可能会增加 与动脉压力感受性反射敏感性减弱有关。即使是在 没有疾病，单独衰老可以减少压力感受性反射介导的心脏迷走神经 血管交感神经流出的反应和压力感受性反射抑制。 与年龄相关的压力感受区更强的僵硬 血管顺应性下降可能是改变的主要罪魁祸首 压力感受器反射功能随年龄增长而变化。此外，更大的适合度与 具有更大的血管顺应性，因此可能有助于保持 压力感受性自主神经循环控制与年龄的关系。拟议的研究 将使用独特的血管超声测量来描述 伸展初级压力感受区，颈动脉至 压力感受器反射介导的青年和青少年心血管自主神经反应 活跃和不活跃的老年人。因此，洞察两国之间的关系 颈动脉血管僵硬和压力反射增强与年龄和健康的关系 将会有所收获。此外，压力感受器传入的直接测量 颈动脉窦神经的活动在急性期增加。 动脉内膜剥脱术中患者动脉压的变化。这将是 提供对压力反射增益的超声评估的验证 颈动脉压与颈动脉压之间的关系 压力感受性传入活动。这种新的压力反射方法 人类的生理学将不仅描绘出颈动脉的作用 动脉压力感受性传入反应的僵硬 压力，也是运动在减少运动影响中的作用 血管僵硬对压力感受器反射功能随年龄的影响。因为 动脉压力感受性反射是决定平均值的主导因素。 心脏迷走神经张力的水平，这些研究可能提示机制 增强迷走神经张力，降低不良后果风险 心血管疾病。

The altered autonomic regulation of the cardiovascular system implicated in the increased incidence of cardiovascular diseases with age is likely related to attenuated arterial baroreflex sensitivity. Even in the absence of disease, aging alone reduces baroreflex-mediated cardiac vagal responses and baroreflex inhibition of vascular sympathetic outflow. Greater stiffness of barosensory areas associated with age-related declines in vascular compliance may be the primary culprit in altered baroreflex function with age. Moreover, greater fitness is associated with greater vascular compliance, and, thus may help to maintain baroreflex autonomic circulatory control with age. The proposed research will use unique vascular ultrasonography measurements to relate the stretch of a primary barosensory region, the carotid artery to baroreflex-mediated cardiovascular autonomic responses in young and active and inactive older humans. Thus, insight to the relations between carotid vascular stiffness and baroreflex gain with aging and fitness will be gained. Moreover, direct measurements of barosensory afferent activity in the carotid sinus nerve will be made during acute increases of arterial pressure in patients during endarterectomy surgery. This will provide a validation of ultrasound derived assessments of baroreflex gain against the relations between carotid arterial pressures and baroreceptive afferent activity. This novel approach to baroreflex physiology in humans will delineate not only the role of carotid stiffness in barosensory afferent responses to increases in arterial pressure, but also the role of exercise in reducing the effect of vascular stiffness on attenuated baroreflex function with age. Because the arterial baroreflex is the dominant factor which determines the mean level of cardiac vagal tone, these studies may suggest mechanisms to enhance vagal tone and decrease the risk of adverse outcomes with cardiovascular diseases.