Korean J Obstet Gynecol.  1999 May;42(5):968-974.

Immunohistochemical Localization of Endothelial Nitric Oxide Synthase in Normotensive and Preeclamptic Placentas

Abstract


OBJECTIVE
Endothelial isoform of nitric oxide synthase[eNOS] regulates the vascular resistance by producing nitric oxide[NO], endothelium-derived relaxing factor. The purpose of this study was to compare the expression of eNOS by immunohistochemical staining in the placentas and umbilical vessels of preeclamptic pregnancies with that of normotensive pregnancies.
METHODS
Placentas and umbilical vessels were examined from 5 preeclamptic pregnancies and 5 normotensive pregnancies. Frozen sections of umbilical cords, chorionic plate vessels, and terminal villi were immuno-stained with a monoclonal eNOS antibody[H32]. Mann-Whitney U test and Fisher`s exact test were used where appropriate, and p value < 0.05 was taken to be significant.
RESULTS
No differences in eNOS immuno-staining in the endothelium of chorionic plate vessels and stem villous vessels were found between preeclamptic and normotensive pregnancies. In the syncytiotrophoblast, eNOS immunostaining appeared diffusely in distribution in both the preeclamptic and normotensive placentas. In contrast, eNOS expression was only observed in the small terminal villous vessels with underlying smooth muscle layer in the preeclamptic placentas[p<0.05].
CONCLUSION
Increased eNOS expression in terminal villous vessels in preeclampsia may be the result of vascular alterations or damage that take place in the placenta, and may be an adaptive response to the increased resistance and poor perfusion in this pathological pregnancies.

Keyword

preeclampsia; placenta; nitric oxide synthase; nitric oxide

MeSH Terms

Chorion
Endothelium
Endothelium-Dependent Relaxing Factors
Frozen Sections
Muscle, Smooth
Nitric Oxide
Nitric Oxide Synthase
Nitric Oxide Synthase Type III*
Perfusion
Placenta*
Pre-Eclampsia
Pregnancy
Trophoblasts
Umbilical Cord
Vascular Resistance
Endothelium-Dependent Relaxing Factors
Nitric Oxide
Nitric Oxide Synthase
Nitric Oxide Synthase Type III
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