Effect of endothelin-1 on the uterine vasculature of the pregnant and estrogen-treated nonpregnant sheep.
OBJECTIVE
This study was designed to evaluate the uterine vascular responses to endothelin-1 in pregnant and estrogen-treated nonpregnant sheep.


METHODS
Seven pregnant and five nonpregnant oophorectomized ewes received local uterine artery infusions of endothelin-1, norepinephrine, and phenylephrine. Arterial blood pressure, heart rate, and uterine blood flow were recorded.


RESULTS
Endothelin-1 (0.01 to 3.0 micrograms/min), norepinephrine (0.1 to 3 micrograms/min), and phenylephrine (0.1 to 10 micrograms) produced significant dose-related decreases in uterine blood flow and increases in uterine vascular resistance. On a nanomoles infused per minute basis, endothelin-1 was much more potent than norepinephrine and phenylephrine as a uterine artery vasoconstrictor in both pregnant and nonpregnant sheep. The uterine vascular responses to norepinephrine and phenylephrine were similar in pregnant and nonpregnant ewes, whereas response to endothelin-1 was blunted in pregnancy.


CONCLUSIONS
Endothelin-1 is an extremely potent uterine vasoconstrictor in both pregnant and nonpregnant ewes, but the uterine vascular responsiveness to endothelin-1 is decreased in pregnancy.
Yang
D
D
Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, OH 45267-0526.
Clark
K E
KE
D000818:Animals; D001808:Blood Vessels / Q000187:drug effects; D016232:Endothelins / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D007269:Injections, Intra-Arterial; D009638:Norepinephrine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects; D012756:Sheep; D014599:Uterus / Q000098:blood supply*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D016232:Endothelins; D004967:Estrogens; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D009638:Norepinephrine