Chelko Stephen P, Schmiedt Chad W, Lewis Tristan H, Lewis Stephen J, Robertson Tom P
Department of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Md., USA.
J Vasc Res. 2013;50(6):478-85. doi: 10.1159/000355265. Epub 2013 Oct 29.
Circulating factors delivered to the nodose ganglion (NG) by the occipital artery (OA) have been shown to affect vagal afferent activity, and thus the contractile state of the OA may influence blood flow to the NG.
OA were isolated and bisected into proximal and distal segments relative to the external carotid artery.
Bisection highlighted stark differences between maximal contractile responses and OA sensitivity. Specifically, maximum responses to vasopressin and the V1 receptor agonist were significantly higher in distal than proximal segments. Distal segments were significantly more sensitive to 5-hydroxytryptamine (5-HT) and the 5-HT2 receptor agonist than proximal segments. Angiotensin II (AT)2, V2 and 5-HT(1B/1D) receptor agonists did not elicit vascular responses. Additionally, AT1 receptor agonists elicited mild, yet not significantly different maximal responses between segments.
The results of this study are consistent with contractile properties of rat OA being mediated via AT1, V1 and 5-HT2 receptors and dependent upon the OA segment. Furthermore, vasopressin-induced constriction of the OA, regardless of a bolus dose or a first and second concentration-response curve, retained this unique segmental difference. We hypothesize that these segmental differences may be important in the regulation of blood flow through the OA in health and disease.
已证明枕动脉（OA）输送至结状神经节（NG）的循环因子会影响迷走神经传入活动，因此OA的收缩状态可能会影响流向NG的血流量。
分离出OA，并相对于颈外动脉将其分为近端和远端节段。
切断突出了最大收缩反应和OA敏感性之间的明显差异。具体而言，远端节段对血管加压素和V1受体激动剂的最大反应明显高于近端节段。远端节段对5-羟色胺（5-HT）和5-HT2受体激动剂的敏感性明显高于近端节段。血管紧张素II（AT）2、V2和5-HT（1B/1D）受体激动剂未引起血管反应。此外，AT1受体激动剂引起的最大反应轻微，但节段间无显著差异。
本研究结果与大鼠OA的收缩特性通过AT1、V1和5-HT2受体介导且依赖于OA节段一致。此外，无论推注剂量或第一和第二浓度-反应曲线如何，血管加压素诱导的OA收缩都保留了这种独特的节段差异。我们假设这些节段差异可能在健康和疾病状态下OA血流调节中起重要作用。
