Plasma- and urine concentrations of nitrite/nitrate and cyclic Guanosinemonophosphate in intrauterine growth restricted and preeclamptic pregnancies.
BACKGROUND
The Nitric Oxide (NO) system plays an important role in the establishment and maintenance of the feto-placental circulation. Research on the pathogenesis of preeclampsia in several studies has established the involvement of the NO-system in preeclampsia and fetal intrauterine growth restriction (IUGR). In the presented study we analyzed the urine and plasma concentrations of nitrite/nitrate, the stable endproducts of NO and its second messenger, cyclic Guanosinemonophosphate (cGMP) in normal, preeclamptic and IUGR pregnancies.


METHODS
In total 76 patients were investigated in a prospective study for repeated determination of plasma and urinary levels of nitrate/nitrite and cGMP: 49 patients with a normal course of pregnancy, 14 patients with fetal IUGR and 13 patients with preeclampsia were included into the study. Plasma and urine Nitrite/Nitrate-concentrations were determined using a Colorimetric Assay (Cayman Inc., USA), concentrations of the second messenger cGMP in plasma and urinary samples were determined with a J(125)-Radio-Immuno-Assay (ibl Inc., Germany). The Stat View Program (Abacus Concepts, Inc., Berkeley, CA, 1992-1998) was used for statistical analysis, a P value <0.05 was considered significant.


RESULTS
Analyzing the data with the Kruskall-Wallis test a significance was reached for Plasma Nitrite/Nitrate (P=0.0236), plasma cGMP (P=0.004) and urinary nitrite/nitrate (P=0.032). No significance was seen for urinary cGMP (P=0.656). Comparing normal and preeclamptic and normal and IUGR pregnancies the following significant differences were seen (Mann-Whitney U test): In preeclamptic pregnancies urine nitrite/nitrate concentration was significantly lower compared to normal pregnancies (P=0.009) No significant difference between normal and preeclamptic pregnancies for plasma nitrite/nitrate (P=0.819) and plasma-cGMP (P=0.072) could be observed. In IUGR pregnancies plasma nitrite/nitrate and the plasma-cGMP concentrations were both significantly lower compared to normal pregnancies (P=0.0077 and 0.0066) in IUGR-pregnancies. No significance was reached when analyzing urine-Nitrite/Nitrate (P=0.7).


CONCLUSIONS
Whereas in preeclampsia a reduced urinary nitrite/nitrate was analyzed, IUGR pregnancies showed reduced plasma nitrite/nitrate and cGMP. A reduced release of NO into the maternal circulation might lead to the presented findings and be involved in the pathogenesis of preeclampsia and fetal IUGR.
Schiessl
Barbara
B
Department of Obstetrics and Gynaecology, Fetal Medicine Unit, Ludwig-Maximilians University, 80337 Munich, Germany. Barbara.Schiessl@med.uni-muenchen.de
Strasburger
Christian
C
Bidlingmaier
Martin
M
Mylonas
Ioannis
I
Jeschke
Udo
U
Kainer
Franz
F
Friese
Klaus
K
D001724:Birth Weight; D006152:Cyclic GMP / Q000097:blood / Q000378:metabolism* / Q000652:urine; D005260:Female; D005317:Fetal Growth Retardation / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D009566:Nitrates / Q000097:blood / Q000378:metabolism* / Q000652:urine; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000097:blood / Q000378:metabolism* / Q000652:urine; D011225:Pre-Eclampsia / Q000378:metabolism*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies
D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D006152:Cyclic GMP