Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom.
Physical Activity for Health and Well-Being Centre, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, United Kingdom.
Am J Physiol Heart Circ Physiol. 2020 Aug 1;319(2):H370-H376. doi: 10.1152/ajpheart.00265.2020. Epub 2020 Jul 10.
Changes in the arterial baroreflex arc contribute to elevated sympathetic outflow and altered reflex control of blood pressure with human aging. Using ultrasound and sympathetic microneurography (muscle sympathetic nerve activity, MSNA) we investigated the relationships between aortic and carotid artery wall tension (indices of baroreceptor activation) and the vascular sympathetic baroreflex operating point (OP; MSNA burst incidence) in healthy, normotensive young ( = 27, 23 ± 3 yr) and middle-aged men ( = 22, 55 ± 4 yr). In young men, the OP was positively related to the magnitude and rate of unloading and time spent unloaded in the aortic artery ( = 0.56, 0.65, and 0.51, = 0.02, 0.003, and 0.03), but not related to the magnitude or rate of unloading or time spent unloaded in the carotid artery ( = -0.32, -0.07, and 0.06, = 0.25, 0.81, and 0.85). In contrast, in middle-aged men, the OP was not related to either the magnitude or rate of unloading or time spent unloaded in the aortic ( = 0.22, 0.21, and 0.27, = 0.41, 0.43, and 0.31) or carotid artery ( = 0.06, 0.28, and -0.01; = 0.48, 0.25, and 0.98). In conclusion, in young men, aortic unloading mechanics may play a role in determining the vascular sympathetic baroreflex OP. In contrast, in middle-aged men, barosensory vessel unloading mechanics do not appear to determine the vascular sympathetic baroreflex OP and, therefore, do not contribute to age-related arterial baroreflex resetting and increased resting MSNA. We assessed the influence of barosensory vessel mechanics (magnitude and rate of unloading and time spent unloaded) as a surrogate for baroreceptor unloading. In young men, aortic unloading mechanics are important in regulating the operating point of the vascular sympathetic baroreflex, whereas in middle-aged men, these arterial mechanics do not influence this operating point. The age-related increase in resting muscle sympathetic nerve activity does not appear to be driven by altered baroreceptor input from stiffer barosensory vessels.
动脉压力感受反射弧的变化导致交感神经输出增加，并改变了人类衰老时血压的反射控制。我们使用超声和交感神经微神经记录（肌肉交感神经活动，MSNA）来研究健康、血压正常的年轻男性（= 27，23±3 岁）和中年男性（= 22，55±4 岁）中主动脉和颈动脉壁张力（压力感受器激活指数）与血管交感神经压力反射操作点（MSNA 爆发发生率）之间的关系。在年轻男性中，OP 与主动脉的卸载幅度和卸载速率以及卸载时间呈正相关（=0.56、0.65 和 0.51，=0.02、0.003 和 0.03），但与颈动脉的卸载幅度或卸载速率或卸载时间无关（=0.32、-0.07 和 0.06，=0.25、0.81 和 0.85）。相比之下，在中年男性中，OP 与主动脉的卸载幅度或卸载速率或卸载时间均无相关性（=0.22、0.21 和 0.27，=0.41、0.43 和 0.31）或颈动脉（=0.06、0.28 和-0.01；=0.48、0.25 和 0.98）。总之，在年轻男性中，主动脉卸载力学可能在确定血管交感神经压力反射的操作点方面发挥作用。相比之下，在中年男性中，压力感受器血管卸载力学似乎并不能决定血管交感神经压力反射的操作点，因此不会导致与年龄相关的动脉压力感受反射重置和静息状态下 MSNA 的增加。我们评估了压力感受器血管力学（卸载幅度和速率以及卸载时间）作为压力感受器卸载的替代指标的影响。在年轻男性中，主动脉卸载力学在调节血管交感神经压力反射的操作点方面很重要，而在中年男性中，这些动脉力学不会影响这个操作点。静息状态下肌肉交感神经活动的增加似乎不是由来自更硬的压力感受器血管的传入变化引起的。
