Existence of Compensatory Defense Mechanisms Against Oxidative Stress and Hypertension in Preeclampsia

Objective: Preeclampsia is a complex obstetrical syndrome characterized by hypertension and proteinuria. This syndrome is associated with oxidative stress, antioxidant imbalance and impaired production of vasoactive eicosanoids such as thromboxane A(2) (TXA(2)), a potent vasoconstrictor, and prostacyclin (PGI(2)), a well-known vasodilator. We hypothesized that there was a relationship between antioxidant vitamins, such as vitamin E and coenzyme Q(10) (CoQ(10)), and the production of vasoactive eicosanoids-PGI(2) and TXA(2)-Potentially regulated by pro-oxidants and antioxidants in preeclampsia. Methods: Therefore, the plasma levels of vitamin E, CoQ(10,) TXA(2) and PGI(2) in normotensive (n = 30) and preeclamptic (n = 29) pregnancies were evaluated. Reduced and oxidized forms of vitamin E and CoQ(10) in blood were measured using a HPLC coupled to electrochemical detection. The levels of TXB2 and 6-keto-PGF(1 alpha), stable metabolites of TXA(2) and PGI(2) respectively, were measured by ELISA. Results: The CoQ(10) oxidized/reduced ratio was significantly higher in preeclamptic compared to normotensive pregnancies (P = 0.04). A strong correlation between plasma levels of reduced vitamin E and CoQ(10), corrected for apolipoprotein B, was observed only in preeclampsia (r = 0.69, P < 0.0001). The 6-keto-PGF(1 alpha)/TXB2 ratio was higher in preeclampsia than in controls (P = 0.02), and this ratio was correlated to the oxidized/reduced ratio of both, vitamin E and CoQ(10) in all pregnancies (p < 0.023). Conclusion: The data indicated that CoQ(10) is a sensitive marker of oxidative stress in preeclampsia. The correlation between vitamin E and CoQ(10) suggested a coordinated defense mechanism against oxidation. Furthermore, the higher 6-keto-PGF(1 alpha)/TXB2 ratio that strongly correlated with oxidative stress markers, suggests a mechanism developed by the maternal cardiovascular system to counteract hypertension during preeclampsia.