PP075. Endothelial dysfunction may be impaired by increased oxidative stress in preeclamptic women

The essential pathogenesis in preeclampsia is vasospasm induced by endothelial cell injury. The vascular endothelium regulates vascular smooth muscle tone by producing vasoconstrictors and vasodilators, such as nitric oxide (NO). Recently, it has been reported that the levels of oxidative stress are increased and they may impair endothelial NO production and induce endothelial dysfunction in preeclampsia.

To determine whether maternal release of oxygen free radical and antioxidants are associated with maternal vascular endothelial cell injury, we measured serum parameters of oxidative stress and endothelial function during pregnancy in women with or without preeclampsia.

We evaluated 20 participants with uncomplicated pregnancies, 15 with mild preeclampsia, and 18 with severe preeclampsia. Plasma concentrations were measured for derivatives of reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) as markers of oxygen free radicals and antioxidants, respectively. Flow-mediated vasodilation (FMD) was also assessed as a marker of endothelial function.

D-ROMs were increased in the maternal blood of the severe preeclamptic group compared with the control group (681.0±239.0 vs 478.6±101.4 CARR U, P<0.001), but not in the mild preeclamptic group (562.0±106.5 CARR U). Plasma BAP levels did not change significant in all three groups. The proportion of d-ROMs to BAP was higher in the severe preeclamptic group than in controls (0.28±0.11 vs 0.21±0.05, P<0.01), but not in the mild preeclamptic group (0.24±0.08). FMD was significantly decreased in both preeclamptic groups (severe, 4.3±3.3%, P<0.001; mild, 6.5±3.6%, P<0.001) compared with controls (10.5±2.3%), but FMD in the severe preeclamptic group was significantly greater than in the mild preeclamptic group. A negative correlation between FMD and d-ROM concentrations was observed in all participants (r=-0.376, P<0.05), and the ratio of serum d-ROMsto BAP correlated negatively with FMD (r=-0.413, P<0.05) in all participants.

We found that the production of oxygen free radicals increased, but not the production of antioxidants which decreased, as a result, an imbalance between reactive oxygen species formation and antioxidant defence mechanisms may have impaired endothelial function in preeclamptic women.