In Vitro Vascular Relaxation to Progesterone and its Metabolites in Human Umbilical and Placental Blood VesselsJournal of Maternal-Fetal Investigation (1998)
Background: We have recently reported that progesterone caused a receptor-mediated, cAMP-dependent relaxation in isolated placental arteries and veins from normal term pregnancies that may be important in maintaining adequate blood flow in the placental circulation. Objective: To further investigate the activity of progesterone and some of its metabolites in both placental and umbilical vessels. Study design: Isolated human placental and umbilical arteries and veins from normal term pregnancies, incubated in Krebs-bicarbonate buffer and submaximally precontracted with potassium chloride, were exposed to cumulative concentrations (0.01-30 µm) of progesterone, 5beta-pregnane-3,20-dione, 5alpha-pregnane-3,20-dione, or 5alpha-pregnane-3beta-ol-20-one. Results: All experimental progestins produced concentration-dependent relaxations in precontracted human placental and umbilical arteries and veins. These relaxations were endothelium-independent. Progesterone and 5beta-pregnane-3,20-dione appeared to be the most potent and efficient of the tested progestins, whereas 5alpha-pregnane-3beta-ol-20-one produced the least relaxation in the same vessels. Conclusions: These results suggest that not only progesterone, but also its metabolites, may be of physiological importance in the regulation of umbilico-placental vascular tone. Additionally, it appears that the umbilical blood vessels possess the same relaxation to progesterone as placental arteries and veins. Taken together, these results indicate a potential role for progesterone and its metabolites in maintaining adequate blood flow in the umbilico-placental circulation.
- in vitro,
- vascular relaxation,
Publication DateJune, 1998
Citation InformationR. Ramirez, M. Gibson, J. Kalenic, S. Einzig, et al.. "In Vitro Vascular Relaxation to Progesterone and its Metabolites in Human Umbilical and Placental Blood Vessels" Journal of Maternal-Fetal Investigation Vol. 8 Iss. 2 (1998) p. 61 - 65
Available at: http://works.bepress.com/hatim_omar/72/