Prostaglandin I2 mediates weak vasodilatation in human placental microvessels

Abstract

Human placental vessels (HPVs) play important roles in the exchange of metabolites and oxygen in maternal-fetal circulation. Endothelial-derived prostacyclin (prostaglandin I2, PGI2) is a critical endothelial vasodilator in the body. However, the physiological and pharmacological functions of endothelial PGI2 in the human placenta are still unclear. Human, sheep, and rat blood vessels were used in this study. Unlike non-placental vessels (non-PVs), the PGI2 synthesis inhibitor tranylcypromine (TCP) did not modify 5-hydroxytryptamine (5-HT)-induced vascular contraction, indicating that endothelial-derived PGI2 was weak in placental vessels (PVs). Vascular responses to exogenous PGI2 showed slight relaxation followed by a significant contraction at a higher concentration in HPV, which was inhibited by the thromboxane-prostanoid (TP) receptors antagonist SQ-29,548. Testing PVs and non-PVs from sheep also showed similar functional results. More TP receptors than PGI2 (IP) receptors were observed in HPVs. The whole-cell K+ current density of HPVs was significantly weaker than that of non-PVs. This study demonstrated the specific characteristics of the placental endogenous endothelial PGI2 system and the patterns of placental vascular physiological/pharmacological response to exogenous PGI2, showing that placental endothelial PGI2 dose not markedly contribute to vascular dilation in the human placenta, in notable contrast to non-PVs. The results provide crucial information for understanding the endothelial roles of HPVs, which may be helpful for further investigations of potential targets in the treatment of diseases such as preeclampsia.

Infection with Listeria monocytogenes alters the placental transcriptome and eicosanome

“…We were particularly interested to observe an enrichment of genes associated with eicosanoid biosynthesis and metabolism following infection. Though this result is not entirely surprising due to the role of eicosanoids in inflammation, it was noteworthy considering that eicosanoids are known to play critical roles in the regulation of labor, as well as other aspects of pregnancy such as placental function [30]. Further, this discovery warrants further investigation due to previous associations between placental eicosanoid dysregulation and pathological pregnancy outcomes in previous studies [31].…”

Endothelium‐dependent contraction: The non‐classical action of endothelial prostacyclin, its underlying mechanisms, and implications

“…COX inhibition has been reported to remove EDCF activity that also takes a part in the regulation of human vascular function, especially under disease conditions 34,99,101,124–127 . PGI 2 has been reported to evoke vasoconstrictor effect or to have limited vasodilator effect in some vascular beds of humans 63,64,128 . It should be noted that TP and EP3 are all reported to function and mediate contractions in human vessels 2,4,129–131 .…”

“…34,99,101,[124][125][126][127] PGI 2 has been reported to evoke vasoconstrictor effect or to have limited vasodilator effect in some vascular beds of humans. 63,64,128 It should be noted that TP and EP3 are all reported to function and mediate contractions in human vessels. 2,4,[129][130][131] Moreover, TP has been reported to mediate PGI 2 's vasoconstrictor effect in human renal arteries.…”

“…Also, it remains to be determined whether the weak vasoconstrictor effect of PGI 2 reported in some humans vessels is due to limited vessels studied or the scarce vasodilator effect of low concentrations of PGI 2 shown on some human vascular beds results from the compromising effect of EP3 as we have noted in rat mesenteric resistance arteries. 63,79,128 It needs to be pointed out that although the vasoconstrictor effect of PGI 2 in some vascular beds might be subtle under normal conditions it can significantly increase in diseases. which appears to contradict with the results we found on vessels.…”

A Study on Vascular Regulators as Early Biomarkers of Hand Arm Vibration Syndrome

“…Interleukin (IL)-6, IL-8, angiotensin (Ang) II, and tumor necrosis factor (TNF)-α are important inflammatory factors and are abundantly expressed in the process of vascular injury. [8][9][10] Ang II, thromboxane (TX)A 2 , and ET-1 are vasoconstriction regulators, 11,12 while prostaglandin (PG)I 2 , atrial natriuretic peptide (ANP), and nitric oxide (NO) are vasodilation regulators, [13][14][15] which collectively play an important role in maintaining normal vascular ecology.…”