Effects of progesterone on blood pressure, plasma volume and
responses to hypotension.
Pecins-Thompson, Melanie, and Maureen Keller-Wood.
Department of Pharmacodynamics, University of Florida, Gainesville,
FL 32610
APStracts 3:0298R, 1996.
Gonadal steroids have been implicated in the control of blood pressure
and fluid homeostasis. These experiments test the effect of
progesterone in ovariectomized (OVX) ewes on blood pressure, volume,
and hormone responses to hypotension. Eight ewes were each studied in
4 conditions: ovariectomized, progesterone and estrogen-replaced,
progesterone-replaced, or sham-treated. During each treatment, mean
arterial pressure (MAP), plasma volume (PV), baroreflex
responsiveness, and ACTH, AVP and renin responses to hypotension were
determined. Progesterone treatment significantly reduced resting MAP
and increased PV as compared to ovariectomized or sham treatments.
Heart period at 85 mm Hg was reduced with progesterone treatment.
There was no effect of progesterone treatment on ACTH, AVP or renin
or heart rate responses to hypotension. Basal AVP levels were
increased, and angiotensin II concentrations were decreased, by
estrogen and progesterone and by sham treatments; plasma sodium also
tended to be increased during these treatments. These results suggest
that a small increase in progesterone can reset resting MAP and PV
without altering reflex heart rate or endocrine responses to
hypotension.
Received 12 February 1996; accepted in final form 23 July 1996.
APS Manuscript Number R90-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996