School of Kinesiology, University of Western Ontario, London, Ontario, Canada.
Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada.
Am J Physiol Heart Circ Physiol. 2023 Jan 1;324(1):H100-H108. doi: 10.1152/ajpheart.00377.2022. Epub 2022 Dec 2.
Increasing evidence indicates that cerebrovascular compliance contributes to the dynamic regulation of cerebral blood flow but the mechanisms regulating cerebrovascular compliance in humans are unknown. This retrospective study investigated the impact of neural, endothelial, and myogenic mechanisms on the regulation of vascular compliance in the cerebral vascular bed compared with the forearm vascular bed. An index of vascular compliance () was assessed using a Windkessel model applied to blood pressure waveforms (finger photoplethysmography) and corresponding middle cerebral artery blood velocity or brachial artery blood velocity waveforms (Doppler ultrasound). Data were analyzed during a 5-min baseline period (10 waveforms) under control conditions and during distinct sympathetic blockade (, phentolamine; 10 adults), cholinergic blockade (, glycopyrrolate; 9 adults), and myogenic blockade (, nicardipine; 14 adults). In e, phentolamine increased similarly in the cerebral vascular bed (131 ± 135%) and forearm vascular bed (93 ± 75%; = 0.45). In , glycopyrrolate increased cerebrovascular (72 ± 61%) and forearm vascular (74 ± 64%) to a similar extent ( = 0.88). In , nicardipine increased but to a greater extent in the cerebral vascular bed (88 ± 88%) than forearm vascular bed (20 ± 45%; = 0.01). Therefore, adrenergic, cholinergic, and myogenic mechanisms contribute to the regulation of cerebrovascular and forearm vascular compliance. However, myogenic mechanisms appear to exert more specific control over vascular compliance in the brain relative to the forearm. Vascular compliance represents an important determinant in the dynamics and regulation of blood flow through a vascular bed. However, the mechanisms that regulate vascular compliance remain poorly understood. This study examined the impact of neural, endothelial, and myogenic mechanisms on cerebrovascular compliance compared with forearm vascular compliance. Distinct pharmacological blockade of α-adrenergic, endothelial muscarinic, and myogenic inputs altered cerebrovascular and forearm vascular compliance. These results further our understanding of vascular control and blood flow regulation in the brain.
越来越多的证据表明，脑血管顺应性有助于脑血流的动态调节，但人类调节脑血管顺应性的机制尚不清楚。本回顾性研究比较了大脑血管床与前臂血管床，探讨了神经、内皮和肌源性机制对血管顺应性调节的影响。使用 Windkessel 模型（应用于血压波形（手指光体积描记法）和相应的大脑中动脉血流速度或肱动脉血流速度波形（多普勒超声））评估血管顺应性指数（）。在控制条件下和不同的交感神经阻断（，酚妥拉明；10 名成年人）、胆碱能阻断（，格隆溴铵；9 名成年人）和肌源性阻断（，尼卡地平；14 名成年人）下，分析了 5 分钟基线期（10 个波形）的数据。在 e 中，酚妥拉明增加的程度在大脑血管床（131±135%）和前臂血管床（93±75%；=0.45）中相似。在 中，格隆溴铵增加的程度在大脑血管床（72±61%）和前臂血管床（74±64%）中相似（=0.88）。在 中，尼卡地平增加了血管顺应性，但在大脑血管床（88±88%）中增加的程度大于前臂血管床（20±45%；=0.01）。因此，肾上腺素能、胆碱能和肌源性机制有助于调节脑血管和前臂血管顺应性。然而，与前臂相比，肌源性机制似乎对大脑血管顺应性具有更特定的控制作用。血管顺应性是血管床血流动力学和调节的一个重要决定因素。然而，调节血管顺应性的机制仍知之甚少。本研究比较了大脑血管床与前臂血管床，探讨了神经、内皮和肌源性机制对脑血管顺应性的影响。对α-肾上腺素能、内皮乙酰胆碱能和肌源性输入的特定药理学阻断改变了大脑和前臂血管的顺应性。这些结果进一步加深了我们对大脑血管控制和血流调节的理解。
