Influence of Ovarian Steroid on the Response of Ovine Uterine Arterial Smooth Muscle to Norepinephrine

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Abstract
Twenty ovariectomized ewes were used in an experiment of 2 × 2 factorial design to examine the effects of estradiol-17β and progesterone on the in vitro constriction of uterine arteries. Animals received the following treatments for 4.5 days: 1) corn oil (controls); 2) estradiol-17β (54 ±3mg in silastic capsule implants); 3) progesterone (15 mg injected twice-daily); and 4) estradiol-17β plus progesterone. Vasoconstriction was monitored during perfusion of uterine arterial segments with Krebs Henseleit solution into which was injected saline, norepinephrine (8μg) and saline, respectively, each at 15-min intervals. Progesterone increased (P<.05) while exogenous estradiol-17β decreased (P<.08) the response to norepinephrine compared to responses of arteries of control ewes. Arteries from control and estradiol-17β plus progesterone-treated ewes did not differ in their response to norepinephrine. No constriction of any artery occurred following exposure to saline. These data suggest that ovarian steroids alter the ability of arterial smooth muscle cells to respond to neurotransmitter. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.