AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 5 786-R791, Copyright © 1984 by American Physiological Society
Blood pressure control in pregnant rabbits: norepinephrine and prostaglandin interactions
R. Venuto, I. Min, P. Barone, A. Donker and E. Cunningham
The relationship between norepinephrine (NE) and prostaglandins in the
regulation of systemic blood pressure during pregnancy was examined in
conscious rabbits. The arterial prostaglandin E2 (PGE2) concentration was
higher in pregnant than in nonpregnant rabbits. Resting blood pressure was
slightly lower in the gravid animals. The pressor response to incremental
doses of intravenous NE was blunted in the pregnant rabbits. Meclofenamate,
a cyclooxygenase inhibitor, failed to alter the resting blood pressure in
either group of animals, although it reduced PGE2 levels more than 60% in
the pregnant rabbits. The pressor response to NE was significantly
increased only in the pregnant rabbits when the NE infusion was repeated
following meclofenamate. Pregnant rabbits could also be differentiated from
nonpregnant by their higher peripheral blood levels of NE and their uniform
hypotensive response to alpha-adrenergic blockade. These observations
define an altered responsiveness to both endogenous and exogenous NE in
pregnant rabbits that appears to be related to an increase in vasodilator
prostaglandins.
