Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Division of Cardiology, Department of Medicine, University Health Network and Sinai Health, University of Toronto, Toronto, Ontario, Canada.
Physiol Rep. 2022 Apr;10(8):e15256. doi: 10.14814/phy2.15256.
The study of vascular regulation often omits important information about the elastic properties of arteries under conditions of pulsatile flow. The purpose of this study was to examine the relationship between muscle sympathetic nerve activity (MSNA), vascular bed compliance, and peripheral blood flow responses in humans. We hypothesized that increases in MSNA would correlate with reductions in vascular compliance, and that changes in compliance would correspond with changes in peripheral blood flow during sympatho-excitation. MSNA (microneurography), blood pressure (Finopres), and brachial artery blood flow (Doppler ultrasound), were monitored in six healthy males at baseline and during the last 15 s of voluntary end-inspiratory, expiratory apneas and 5 min of static handgrip exercise (SHG; 20% maximum voluntary contraction) and 3 min of post-exercise circulatory occlusion (SHG + PECO; measured in the non-exercising arm). A lumped Windkessel model was employed to examine vascular bed compliance. During apnea, indices of MSNA were inversely related with vascular compliance, and reductions in compliance correlated with decreased brachial blood flow rate. During SHG, despite increased MSNA, compliance also increased, but was unrelated to increases in blood flow. Neither during SHG nor PECO did indices of MSNA correlate with forearm vascular compliance nor did vascular compliance correlate with brachial flow. However, during PECO, a linear combination of blood pressure and total MSNA was correlated with vascular compliance. These data indicate the elastic components of the forearm vasculature are regulated by adrenergic and myogenic mechanisms during sympatho-excitation, but in a reflex-dependent manner.
在研究血管调节时，通常会忽略脉动流条件下动脉弹性特性的重要信息。本研究旨在探讨人类肌肉交感神经活动（MSNA）、血管床顺应性和外周血流反应之间的关系。我们假设，MSNA 的增加与血管顺应性的降低相关，而顺应性的变化与交感兴奋期间外周血流的变化相对应。在 6 名健康男性中，在基线时以及在自愿吸气末、呼气末呼吸暂停的最后 15 秒和 5 分钟的静态手握运动（SHG；20%最大自主收缩）以及运动后 3 分钟的循环闭塞（SHG+PECO；在非运动侧测量）期间，监测 MSNA（微神经记录）、血压（Finopres）和肱动脉血流（多普勒超声）。采用集总风箱模型来检查血管床顺应性。在呼吸暂停期间，MSNA 的指标与血管顺应性呈负相关，而顺应性的降低与肱动脉血流速率的降低相关。在 SHG 期间，尽管 MSNA 增加，但顺应性也增加，但与血流增加无关。在 SHG 或 PECO 期间，MSNA 的指标均与前臂血管顺应性无关，血管顺应性也与肱动脉血流无关。然而，在 PECO 期间，血压和总 MSNA 的线性组合与血管顺应性相关。这些数据表明，在交感兴奋期间，前臂血管的弹性成分受肾上腺素能和肌源性机制调节，但以反射依赖的方式调节。
