Uterine arterial vasoconstrictions mediated by the ovarian nerves
in virgin and postpartum rats.
Hutchison, Scot M., Amy E. Tietz, Kendrick A. Trostel, Lawrence P.
Schramm.
Departments of Biomedical Engineering, Neuroscience, and Gynecology
and Obstetrics, The Johns Hopkins University School of Medicine, 720
N. Rutland Avenue, Baltimore, Maryland 21205, U.S.A.
APStracts 3:0282R, 1996.
In most mammals, including humans, pregnancy results in the loss of
most uterine vasomotor fibers. These experiments determined whether,
despite this denervation, sympathetic nerves mediated uterine
vasoconstrictions in the rat, 24h after delivery. Both virgin and
uniparous postpartum rats were anesthetized with urethane. Femoral
vessels were cannulated for measurement of arterial pressure and
intravenous administration of fluids and drugs. Blood flow was
measured in a uterine artery after ligation of all anastomotic
ovarian vessels. Electrical stimulation of ovarian nerve efferents
elicited frequency-dependent uterine vasoconstrictions in both virgin
and postpartum rats. Vasoconstrictions in postpartum rats were not
significantly different from those observed in virgins. In both
virgin and postpartum rats, neurogenic vasoconstrictions were reduced
by combined [alpha]1- and [alpha]2-adrenergic blockade. We conclude
that the uterine branches of the ovarian nerve mediate adrenergic
uterine vasoconstrictions. In the largely-denervated uterus of the
postpartum rat, these vasoconstrictions may be mediated by surviving
innervation of the uterine artery and its major branches. Sympathetic
vasoconstriction acting at these sites would constitute an effective
defense against postpartum hemorrhage.
Received 26 December 1995; accepted in final form 20 June 1996.
APS Manuscript Number R816-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996