Female reproductive cycle influences plasma volume and protein
restitution after hemorrhage in the conscious rat.
Slimmer, L. M., and M. L. Blair.
Department of Physiology, University of Rochester School of
Medicine and Dentistry, Rochester, NY 14642
APStracts 3:0112R, 1996.
The present study was designed to test the hypothesis that gender and
female reproductive cycle phase influence the restitution of blood
volume following blood loss. The experiments were performed in
conscious 9-11 week old Sprague-Dawley rats subjected to a slow
hemorrhage of 19 ml/kg over 40 minutes. The effect of hemorrhage was
compared in male rats and in female rats in either proestrus (PRO) or
metestrus (MET). In comparison with either metestrus females or
males, females hemorrhaged on the morning of proestrus showed a
significantly larger overall decrease in percent hematocrit (PRO,
-17+1; MET, -10+1; male, -13+1; mean + S.E.), increase in plasma
volume (PRO, to 151+15% of initial volume; MET, 104+8%; male, 120+4%)
and increase in total plasma protein content (PRO, to 164+14% of
initial content; MET, 101+5%; male, 132+5%) over the 21-hr post
-hemorrhage recovery period. Proestrus females also showed a larger
increase in plasma osmolality during the first 2.5 hr post-hemorrhage
than either metestrus females or males (p<.05). In addition,
basal hematocrit and total blood volume (Cr51-tagged erythrocyte
method) were higher in females studied on the morning of proestrus
than in metestrus females. These results indicate that the female
reproductive cycle is an important variable in basal blood volume
regulation and in plasma protein and plasma volume restitution
following blood loss.
Received 31 July 1995; accepted in final form 12 March 1996.
APS Manuscript Number R476-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96