W. B. Farquhar: 541 South College Avenue, Fred Rust HPL - Office #143, Newark, DE 19716, USA.
Exp Physiol. 2013 Oct;98(10):1422-31. doi: 10.1113/expphysiol.2013.073189. Epub 2013 Jun 3.
Sympathetic baroreflex sensitivity is increased during selective activation of the skeletal muscle metaboreflex with postexercise ischaemia (PEI) in young adults. However, to date, there are no data demonstrating this neural interaction between the arterial baroreflex and the muscle metaboreflex in healthy older adults. Therefore, the goal of the present study was to examine the influence of healthy ageing on the metabolic component of the exercise pressor reflex and its interaction with the arterial baroreflex in the control of sympathetic outflow. Postexercise ischaemia following static hand grip performed at 30% maximal voluntary contraction was used to isolate muscle metaboreflex activation in young [n = 10; 24 ± 1 years old; resting blood pressure (BP) 116 ± 3/64 ± 3 mmHg] and older men (n = 9; 59 ± 2 years old; resting BP 120 ± 2/77 ± 2 mmHg). Arterial BP (Finometer) and muscle sympathetic nerve activity (MSNA) were measured continuously. Weighted linear regression analysis between MSNA and diastolic BP was used to estimate arterial baroreflex MSNA gain. There were no age-related differences in the increase in mean BP (young, Δ14 ± 3 mmHg versus older, Δ15 ± 2 mmHg; P > 0.05) or MSNA burst frequency (young, Δ11 ± 2 bursts min(-1) versus older, Δ9 ± 1 bursts min(-1); P > 0.05) during PEI. Likewise, the gain of arterial baroreflex control of total MSNA increased to a similar extent in both groups during PEI (young, -4.2 ± 0.9 baseline versus -6.3 ± 1.1 PEI a.u. beat(-1) mmHg(-1); and older, -3.7 ± 1.1 baseline versus -6.7 ± 1.4 PEI a.u. beat(-1) mmHg(-1); P < 0.05 for both). Collectively, these findings indicate that the neural interaction between the arterial baroreflex and the skeletal muscle metaboreflex in the regulation of MSNA is preserved in healthy ageing.
在年轻人中，选择性激活骨骼肌代谢反射后进行运动后缺血（PEI）会导致交感神经反射敏感性增加。然而，迄今为止，尚无数据表明健康老年人的动脉压力反射和肌肉代谢反射之间存在这种神经相互作用。因此，本研究的目的是研究健康衰老对运动加压反射代谢成分的影响及其对控制交感神经输出的动脉压力反射的相互作用。在年轻人[n = 10；24 ± 1 岁；静息血压（BP）116 ± 3/64 ± 3 mmHg]和老年人[n = 9；59 ± 2 岁；静息 BP 120 ± 2/77 ± 2 mmHg]中，使用 30%最大自主收缩时的静态握力后进行的运动后缺血，用于分离肌肉代谢反射的激活。连续测量动脉血压（Finometer）和肌肉交感神经活动（MSNA）。使用 MSNA 与舒张压之间的加权线性回归分析来估计动脉压力反射 MSNA 增益。在 PEI 期间，平均 BP 的增加（年轻人，Δ14 ± 3 mmHg 与老年人，Δ15 ± 2 mmHg；P > 0.05）或 MSNA 爆发频率（年轻人，Δ11 ± 2 次爆发 min(-1) 与老年人，Δ9 ± 1 次爆发 min(-1)；P > 0.05）与年龄无关。同样，在 PEI 期间，两组的动脉压力反射对总 MSNA 的控制增益增加到相似程度（年轻人，-4.2 ± 0.9 基线与-6.3 ± 1.1 PEI a.u. beat(-1) mmHg(-1)；老年人，-3.7 ± 1.1 基线与-6.7 ± 1.4 PEI a.u. beat(-1) mmHg(-1)；两者均 P < 0.05）。总的来说，这些发现表明，在健康衰老中，调节 MSNA 的动脉压力反射和骨骼肌代谢反射之间的神经相互作用得以保留。
