title: Regulation of prostacyclin and thromboxane production by human umbilical vessels: the effect of estradiol and progesterone in a superfusion model.
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.
mesh_terms: D015121:6-Ketoprostaglandin F1 alpha / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D011464:Epoprostenol / Q000096:biosynthesis*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D011453:Prostaglandins / Q000096:biosynthesis*; D013929:Thromboxane B2 / Q000096:biosynthesis*; D013931:Thromboxanes / Q000096:biosynthesis*; D014469:Umbilical Arteries / Q000187:drug effects* / Q000378:metabolism; D014471:Umbilical Veins / Q000187:drug effects* / Q000378:metabolism
chemical_list: D011453:Prostaglandins; D013931:Thromboxanes; D011374:Progesterone; D004958:Estradiol; D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha; D011464:Epoprostenol