Hypertension induced by episodic reductions in uteroplacental blood flow in gravid rat.
BACKGROUND
The etiology of preeclampsia remains unclear. Animal modeling of preeclampsia has been useful; however, no model to date represents episodic changes in uteroplacental blood flow that may occur in preeclampsia.


OBJECTIVE
To develop a gravid rat model characterized by episodic reductions in uteroplacental blood flow.


METHODS
Pregnant Sprague Dawley rats were used and subjected to SHAM, reduced uterine perfusion pressure (RUPP), or aortic occlusion on gestational Day 14. Aortic occlusion surgery consisted of implantation of a silastic vascular occluder around the abdominal aorta and silver clips around the uterine-ovarian arteries. Aortic occlusion animals were subjected to five consecutive days of occlusion (40% reduction) each session lasting 1 h. On Day 21, maternal mean arterial pressure (MAP) and fetal morphology were assessed. For isolated blood vessels, resistance-sized mesenteric arteries were harvested and mounted on a pressure arteriograph.


RESULTS
Occluder animals experienced a 10 mmHg rise in MAP as compared to SHAM (p < 0.05), and RUPP MAP was significantly increased as compared to control subjects (p < 0.05). Pups from Occluder animals exhibited a decrease in fetal weight as compared to SHAM (p < 0.05), but an increase in fetal weight as compared to RUPP (p < 0.05). Myogenic reactivity of second-order mesenteric arteries increased in Occluder animals as compared to SHAM (p < 0.05), but were similar to that of RUPP.


CONCLUSIONS
Episodic reductions in uteroplacental blood flow play a crucial role in the altered vascular reactivity seen in Occluder animals and may represent a new model to investigate the mechanisms associated with episodic reductions in uteroplacental blood flow in pathological pregnancies.
Reho
John J
JJ
Program in Integrated Biosciences, The University of Akron, Akron, OH 44325, USA.
Peck
Jennifer
J
Novak
Jacqueline
J
Ramirez
Rolando J
RJ
D000704:Analysis of Variance; D000818:Animals; D005260:Female; D046110:Hypertension, Pregnancy-Induced / Q000209:etiology* / Q000503:physiopathology; D010920:Placenta / Q000098:blood supply* / Q000503:physiopathology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000502:physiology*; D014599:Uterus / Q000098:blood supply* / Q000503:physiopathology