Chaudhuri G, Cuevas J, Buga G M, Ignarro L J
Department of Obstetrics and Gynecology, University of California Los Angeles School of Medicine 90024-1740.
Am J Physiol. 1993 Dec;265(6 Pt 2):H2036-43. doi: 10.1152/ajpheart.1993.265.6.H2036.
The endothelial cells of the human umbilical artery and vein release the vasodilators prostacyclin [prostaglandin (PG) I2] and nitric oxide (NO). However, the role of these two substances in the maintenance of vasodilator tone in the feto-placental circulation is not known. Studies were therefore undertaken to compare the relative release of PGI2 and NO from perfused segments (10 cm) of endothelium-intact human umbilical artery (HUA) and vein (HUV) utilizing the cascade bioassay. The endothelium-denuded bovine pulmonary arterial strip was used as the detector tissue because this tissue relaxes equally to various concentrations of PGI2 and S-nitroso-N-acetylpenicillimine (SNAP), which acts by releasing NO. The basal release of NO from the HUA was approximately five times greater than that of PGI2. After stimulation with A-23187, the release of NO from HUV was five to six times greater, and from the HUA, the release was three times greater compared with the PGI2. SNAP was significantly more potent compared with PGI2 in relaxing endothelium-denuded rings of human umbilical and chorionic plate arteries in vitro. These studies suggest that NO is more important than PGI2 for maintenance of low vascular tone in feto-placental vessels, because there is a greater release of NO from the HUA and HUV, and NO is more potent in relaxing endothelium-denuded feto-placental vessels in vitro relative to PGI2.
人脐动脉和静脉的内皮细胞可释放血管舒张剂前列环素[前列腺素(PG)I2]和一氧化氮(NO)。然而，这两种物质在维持胎儿-胎盘循环中血管舒张张力方面的作用尚不清楚。因此，我们进行了一些研究，利用级联生物测定法比较完整内皮的人脐动脉(HUA)和静脉(HUV)灌注段(10厘米)中PGI2和NO的相对释放量。内皮剥脱的牛肺动脉条用作检测组织，因为该组织对不同浓度的PGI2和通过释放NO起作用的S-亚硝基-N-乙酰青霉胺(SNAP)具有同等程度的舒张反应。HUA中NO的基础释放量约为PGI2的五倍。用A-23187刺激后，HUV中NO的释放量比PGI2大五到六倍，而HUA中NO的释放量比PGI2大三倍。在体外，SNAP在舒张人脐动脉和绒毛膜板动脉的内皮剥脱环方面比PGI2更有效。这些研究表明，对于维持胎儿-胎盘血管的低血管张力，NO比PGI2更重要，因为HUA和HUV中NO的释放量更大，而且相对于PGI2，NO在体外舒张内皮剥脱的胎儿-胎盘血管方面更有效。
