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Placental nitric oxide synthase (NOS) activity and nitric oxide (NO) production in normal pregnancy, pre‐eclampsia and eclampsia
Author(s) -
Shaamash A.H.,
Elsonosy E.D.,
Zakhari M.M.,
Radwan Sh.H.,
ElDien H.M.
Publication year - 2001
Publication title -
international journal of gynecology and obstetrics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.895
H-Index - 97
eISSN - 1879-3479
pISSN - 0020-7292
DOI - 10.1016/s0020-7292(00)00314-3
Subject(s) - eclampsia , nitric oxide , placenta , nitric oxide synthase , preeclampsia , nitrite , pregnancy , methemoglobin , chemistry , medicine , endocrinology , andrology , nitrate , obstetrics , hemoglobin , biology , fetus , genetics , organic chemistry
Objectives : To measure nitric oxide synthase (NOS) activity and total nitrites levels (as an index of nitric oxide ‘NO’ production) in placental villous homogenate of normal, pre‐eclamptic and eclamptic pregnant women. Design : Two groups were studied cross‐sectionally: late pregnant women with pre‐eclampsia and eclampsia ( n =31) and normal pregnant women (all late) as controls ( n =32). Two tissue blocks of whole placenta, each 1×1×1 cm, were collected at delivery and assayed for NOS activity and total nitrite levels. Setting : Department of Obstetrics and Gynecology, Assiut University Hospitals, Egypt. Methods : Placental tissues were homogenized and villous homogenates were assayed for NO production by Griess reaction which measures the combined oxidation products for NO (nitrites and nitrates) after reduction with nitrate reductase. NOS activity was determined by measuring NO synthesis by tissue extracts spectrophotometrically using the oxidation of oxyhemoglobin to methemoglobin by NO. Results : Placental villous homogenates of pregnancies complicated by pre‐eclampsia and eclampsia had significantly higher NOS activity and total nitrites levels compared with those of normal pregnancy [for NOS ( P< 0.0001) and for total nitrites ( P< 0.001)]. Conclusions : (1) Placental NOS activity and NO production are significantly increased in pre‐eclampsia and eclampsia than those of normal pregnancy; this increase was directly related to the severity of this disorder. (2) Such increase possibly represents a physiologic adaptive response to overcome the increased placental vascular resistance and to minimize platelet and leukocyte adhesion to the surface of placental villi or within the intervillous spaces.