Hemodynamic changes in pseudopregnancy in chronically instrumented,
conscious rats.
Slangen, Brigitte F. M., Iris C. M. Out, Carla M. Verkeste, Jos F. M.
Smits, Louis L. H. Peeters.
Department of Obstetrics and Gynecology, University of Limburg,
6200 MD Maastricht, The Netherlands
APStracts 3:0395H, 1996.
It is unclear whether the trophoblast is needed for the normal early
-pregnancy hemodyna mic adaptation. In this study we tested the
hypothesis that the presence of trophoblast is not essential for the
initial hemodynamic adaptation in pregnancy. To this end, we measured
systemic hemodynamics in conscious pseudopregnant rats, and compared
the results with those obtained in a concomitantly studied control
group of virgin rats as well as with a previously studied group of
pregnant rats. The rats were studied daily from day 4 postmating
until day 10 and on days 12, 14, 18 and 20. In pseudopregnant rats,
cardiac output (CO) increased from day 5 onward, to 14 +/- 3% above
the initial value by day 8. This rise in CO was entirely accomplished
by a rise in stroke volume (21 +/- 4% by day 8). Mean arterial
pressure did not change appreciably. Therefore, total peripheral
resistance also decreased by 21 +/- 4% by day 8. Meanwhile, peak
flow, aortic flow acceleration and stroke work, indicators of
myocardial performance, had increased, and the hematocrit had
decreased (15 +/- 1% by day 8). Between day 10 and day 20 the
hemodynamic parameters gradually returned to baseline. We conclude
that systemic hemodynamic changes do take place in pseudopregnancy.
They consist of a rise in CO by a rise in stroke volume, an increase
in myocardial performance and hemodilution. The observed changes
closely resemble those in early normal pregnancy. Therefore we accept
our hypothesis that trophoblast is not essential for the initial
hemodynamic changes in rat pregnancy.
Received 26 March 1996; accepted in final form 30 August 1996.
APS Manuscript Number H284-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996