Increased myogenic responses of resistance-sized mesenteric arteries after reduced uterine perfusion pressure in pregnant rats.
OBJECTIVE
A central component of preeclampsia is a reduction in utero-placental perfusion. We tested the hypothesis that vascular reactivity of second - order mesenteric arteries would be increased in a pregnant rat with reduced uterine perfusion pressure (RUPP).


METHODS
Pregnant 10-12 week old Sprague-Dawley rats underwent RUPP surgery on gestational day 14, and experiments were carried out on day 20. SHAM operated animals were used as controls. Resistance caliber mesenteric arteries (200-250 μm) were isolated, myogenic reactivity and responses to vasoconstrictor and vasodilator agonists were assessed utilizing a pressurized arteriograph system.


RESULTS
RUPP resulted in maternal hypertension and reductions in fetal number and weight. Resistance caliber mesenteric arteries (200-250 μm) were isolated, myogenic reactivity and responses to vasoconstrictor and vasodilator agonists were assessed utilizing a pressurized arteriograph system. Myogenic reactivity responses were normalized as a percent change in vessel diameter from an initial diameter at 20 mmHg. The mesenteric arteries from RUPP animals exhibited a significant increase in myogenic reactivity compared to SHAM controls (p < 0.05). This increased myogenicity was reversed with prostaglandin inhibition, suggesting a role for a vasoconstrictor prostaglandin. In addition to alterations in myogenic reactivity, resistance-sized arteries from RUPP animals have decreased responses to nitric oxide (NO) as evidenced by decreases in responses to methacholine (ME; P < 0.05) and no change in myogenic reactivity after NO synthase blockade.


CONCLUSIONS
RUPP alters the behavior of resistance caliber arteries to favor a more contractile phenotype with decreased in NO responses, which is similar to what is seen in preeclampsia.
Ramirez
Rolando J J
RJ
University of Akron, Department of Biology & Integrative Biology Program, Akron, OH 44325, USA.
Debrah
Julianna
J
Novak
Jacqueline
J
D000818:Animals; D005260:Female; D008638:Mesenteric Arteries / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D011247:Pregnancy; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D014599:Uterus / Q000098:blood supply* / Q000502:physiology*