Prostacyclin rather than nitric oxide lowers human umbilical artery tone in vitro

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.

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Vazoactive Effects of Oxidative Stress Elicited by Hydrogen Peroxide in the Human Umbilical Artery: An <i>in Vitro</i> Study

Pharmacology &amp Pharmacy ◽

10.4236/pp.2011.24045 ◽

2011 ◽

Vol 02 (04) ◽

pp. 347-353

Author(s):

Ipek Duman ◽

Necdet Dogan

Keyword(s):

Oxidative Stress ◽

Hydrogen Peroxide ◽

Umbilical Artery ◽

Human Umbilical Artery

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Responses of nerve-free vessels to vasoactive amines and polypeptides

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1965.208.4.748 ◽

1965 ◽

Vol 208 (4) ◽

pp. 748-753 ◽

Cited By ~ 69

Author(s):

Avril V. Somlyo ◽

Chi-Yuan Woo ◽

Andrew P. Somlyo

Keyword(s):

Umbilical Artery ◽

Main Pulmonary Artery ◽

Umbilical Vessels ◽

Vasoconstrictor Response ◽

Human Umbilical Artery ◽

Vasoconstrictor Effect ◽

Rhythmic Contractions ◽

Synthetic Oxytocin ◽

Indirect Action

Contractile responses of helically cut strips of noninnervated human umbilical artery and vein were determined. Spontaneous, rhythmic contractions were exhibited by both preparations, but were greater in magnitude and duration in umbilical veins. Vasoconstriction elicited by sympathomimetic amines was variable, and generally of a low order. The response to norepinephrine was not potentiated by cocaine (10 µg/ml) but was blocked by Dibenamine (1.0–1.5 µg/ml). Umbilical vasoconstrictor response to tyramine (1.0–10.0 µg/ml) indicated the direct vasoconstrictor effect of this agent. The similar norepinephrine-to-tyramine sensitivity ratios of umbilical vessels and canine main pulmonary artery were interpreted as evidence against the indirect action of tyramine in vitro. Isoproterenol produced no vasodilation in umbilical vessels, suggesting the absence of ß-adrenergic pathways. Oxytocin (>>0.1 mU/ml) was a highly effective umbilical vasoconstrictor. Native and synthetic oxytocin preparations were equiactive and produced tachyphylaxis to each other. Native and synthetic lysine-8-vasopressin (>>0.005 U/ml) and angiotensin amide (>>0.002 µg/ml) produced only minimal and inconsistent vasoconstriction, while serotonin (>>0.004 µg/ml) was as effective as oxytocin.

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