These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Properties of a progesterone-induced relaxation in human placental arteries and veins.
    Author: Omar HA, Ramirez R, Gibson M.
    Journal: J Clin Endocrinol Metab; 1995 Feb; 80(2):370-3. PubMed ID: 7852492.
    Abstract:
    To study the effects of progesterone on placental vascular tone, we used isolated (1-2 mm in diameter) placental arteries and veins from term uncomplicated pregnancies. These vessels, incubated in Krebs buffer (pH 7.4) under 5% O2-5% CO2 (balance N2, PO2 approximately 35 torr) and precontracted with serotonin were exposed to incremental doses of progesterone (0.01-30 mumol/L) in the presence or absence of endothelium, 10 mumol/L indomethacin (inhibits prostaglandin synthesis), 10 mumol/L methylene blue (a soluble guanylate cyclase inhibitor), 100 mumol/L nitro-L-arginine (inhibits L-arginine metabolism), 1 mmol/L isobutylmethylxanthine (a cAMP phosphodiesterase inhibitor), or 30 mumol/L mifepristone (RU 38486, an antiprogestin). Progesterone elicited an acute dose-dependent relaxation in both arteries and veins that was not altered by removal of the endothelium or pretreatment with indomethacin, nitro-L-arginine, or methylene blue, excluding a role for prostaglandins, L-arginine products, or cGMP in mediating this relaxation. However, isobutylmethylxanthine significantly enhanced the relaxation in response to progesterone, suggesting a role for cAMP. RU 38486 inhibited the relaxation by 50-100%, depending on the progesterone dose, consistent with a role for progesterone receptors. These results suggest that progesterone causes a dose-dependent endothelium-independent relaxation of human placental arteries and veins. This relaxation seems to be mediated by a receptor-activated cAMP mechanism and could be physiologically important in maintaining low resistance and adequate blood flow in the placental circulation.
    [Abstract] [Full Text] [Related] [New Search]