Maternal and fetal epoxyeicosatrienoic acids in normotensive and preeclamptic pregnancies.

Background: Epoxyeicosatrienoic acids (EETs) and 20-hydroxyeicosatetraenoic acid (20-HETE) are cytochrome P450 metabolites of arachidonic acid posited to act in the circulatory adaptation to pregnancy and the development of preeclampsia. Red blood cells (RBCs) may function as major contributors of cis- and trans-EETs.
Methods: We performed paired analyses of EETs, dihydroxyeicosatrienoic acids (DHETs), and 20-HETE in RBCs, plasma, and urine from preeclamptic and normotensive pregnant and nonpregnant women. Blood from fetal and maternal circulation was collected. EETs, DHETs, and 20-HETE were analyzed by gas chromatography and liquid chromatography mass spectrometry. Vascular function and inflammation indices were analyzed.
Results: Plasma EET is higher in normotensive (median, range; 9.9, 6.3-25.2ng/mL n = 29) and preeclamptic (10.9, 6.0-48.0ng/mL, n = 19) women than in nonpregnant controls (7.3, 3.7-10.2ng/mL, n = 19) and correlate with RBC EETs, C-reactive protein, and arterial stiffness. Renal production of EETs, measured as urinary DHETs, was reduced in preeclamptic (4.5, 1.6-24.5ng/mg creatinine) compared to normotensive (11.4, 1.6-44.5ng/mg creatinine) pregnancies. EETs are 3- to 5-fold greater in fetoplacental than in maternal circulation (RBCs 36.6, 13.1-69.4 vs. 12.5, 6.4-12.0ng/10(9) cells; plasma 31.6, 8.5-192.6 vs. 12.0, 6.8-48.0ng/mL). Both cis- and trans-EETs are present in fetal RBCs.
Conclusions: RBCs contribute to elevated levels of EETs in the fetoplacental circulation. EETs may modulate systemic and fetoplacental hemodynamics in normal and preeclamptic pregnancies. Decreased renal EET generation may be associated with the development of maternal renal dysfunction and hypertension in preeclampsia.