NO is more important than PGI2 in maintaining low vascular tone in feto-placental vessels
Chaudhuri, G.; Cuevas, J.; Buga, G.M.; Ignarro, L.J.
American Journal of Physiology 265(6 Pt 2): H2036-H2043
1993
ISSN/ISBN: 0002-9513 PMID: 8285242 Document Number: 412711
The endothelial cells of the human umbilical artery and vein release the vasodilators prostacyclin (prostaglandin (PG) I-2) and nitric oxide (NO). However, the role of these two substances in the maintenance of vasodilator tone in the fetoplacental circulation is not known. Studies were therefore undertaken to compare the relative release of PGI-2 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 PGI-2 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 PGI-2. 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 PGI-2. SNAP was significantly more potent compared with PGI-2 in relaxing endothelium-denuded rings of human umbilical and chorionic plate arteries in vitro. These studies suggest that NO is more important than PGI-2 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 PGI-2.