Sexton A J, Loesch A, Turmaine M, Miah S, Burnstock G
Department of Anatomy and Developmental Biology, University College London, UK.
Placenta. 1995 Apr;16(3):277-88. doi: 10.1016/0143-4004(95)90114-0.
Human umbilical vessels are devoid of nerves and therefore endothelial cells may play an important role in the control of fetoplacental blood flow. In this study we examined the pharmacological effects of various substances, known to produce endothelial-mediated vasodilation in many blood vessels, on the human umbilical artery and vein from legal terminations [mean gestational age, 15 (8-17) weeks; n = 12] and normal term vaginal deliveries [mean gestational age, 39 (38-41) weeks; n = 12]. Acetylcholine, adenosine 5'-triphosphate, the calcium ionophore A23187 and substance P had no effect on raised vascular tone, whereas sodium nitroprusside relaxed 5-hydroxytryptamine (5-HT) preconstricted, umbilical artery and vein from both early and late pregnancy. L-NG-Nitroarginine methyl ester (L-NAME) had no effect on basal tone or on high tone, after it was raised by 5-HT. Localization of nitric oxide synthase [NOS, type I (neuronal)] was examined in the same umbilical vessels using electron immunocytochemistry. No NOS-immunoreactive endothelial cells were observed in the umbilical vessels taken during early pregnancy. However, the percentage of NOS-immunoreactive endothelial cells in umbilical artery and vein from late pregnancy was 3 and 10 per cent, respectively. These results suggest that nitric oxide contributes little, if any, to the local control of umbilical blood flow throughout pregnancy, despite the presence of NOS-immunoreactivity in a subpopulation of endothelial cells in late pregnancy.
人脐血管没有神经，因此内皮细胞可能在胎儿 - 胎盘血流控制中发挥重要作用。在本研究中，我们检测了多种已知能在许多血管中产生内皮介导的血管舒张作用的物质，对来自合法终止妊娠（平均孕周15（8 - 17）周；n = 12）和足月阴道分娩（平均孕周39（38 - 41）周；n = 12）的人脐动脉和静脉的药理作用。乙酰胆碱、5'-三磷酸腺苷、钙离子载体A23187和P物质对升高的血管张力没有影响，而硝普钠可使早孕期和晚孕期5 - 羟色胺（5 - HT）预收缩的脐动脉和静脉舒张。L - 硝基精氨酸甲酯（L - NAME）对基础张力或5 - HT升高后的高张力均无影响。使用电子免疫细胞化学方法在相同的脐血管中检测一氧化氮合酶[NOS，I型（神经元型）]的定位。在早孕期获取的脐血管中未观察到NOS免疫反应性内皮细胞。然而，晚孕期脐动脉和静脉中NOS免疫反应性内皮细胞的百分比分别为3%和10%。这些结果表明，尽管晚孕期内皮细胞亚群中存在NOS免疫反应性，但一氧化氮在整个孕期对脐血流的局部控制作用甚微（如果有作用的话）。
