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  • Title: Regulation of prostacyclin and thromboxane production by human umbilical vessels: the effect of estradiol and progesterone in a superfusion model.
    Author: Mäkilä UM, Wahlberg L, Vlinikka L, Ylikorkala O.
    Journal: Prostaglandins Leukot Med; 1982 Feb; 8(2):115-24. PubMed ID: 7043492.
    Abstract:
    To study the production of the vasodilatory prostacyclin (PGI2) and vasoconstrictory thromboxane A2 (TxA2) by the human umbilical vessels, vascular segments collected from the cords of healthy newborns (n = 15) after normal pregnancies were superfused with Eagle's medium at 37 degrees C under continuous oxygenation. The stable metabolites of PGI2 and TxA2, 6-keto-prostaglandin F1 alpha and thromboxane B2 (TxB2) respectively, were measured from the superfusates with radioimmunoassays. All vascular segments studied produced 6-keto-PGF1 alpha and TxB2 without any significant difference between the arteries and veins. 6-keto-PGF1 alpha was produced some 10-15 times more than TxB2. 17-beta-estradiol at concentrations of 10, 100 and 1000 ng/ml dose-dependently stimulated the 6-keto-PGF1 alpha formation, but had no effect on TxB2 generation. Progesterone 50, 500 and 5000 ng/ml caused no changes in 6-keto-PGF1 alpha or TxB2 generations but even the smallest concentration of progesterone abolished the stimulating effect of estradiol. These results thus suggest that the high circulating levels of 17-beta-estradiol and progesterone in the umbilical vessels may be important in the regulation of PGI2 synthesis in the umbilical vessels in vivo.
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