Ethene and other biomarkers of oxidative stress in hypertensive disorders of pregnancy.

Objective: An increase in reactive oxygen species (ROS) and lipid peroxides and a comprised antioxidant status has been implicated in the pathophysiology of severe preeclampsia. This study investigates whether oxidative stress and impaired antioxidant systems also contribute to milder forms of hypertensive disorders in pregnancy. Furthermore, ethene in exhaled air, a noninvasive measure for oxidative stress, was evaluated and compared with two other more established biomarkers.

Methods: Ethene in exhaled air, plasma protein carbonyls, and the ratio of free glutathione/oxidized glutathione (GSHfree/GSHox) as markers for oxidative stress as well as the antioxidants vitamins C and E, uric acid, glutathione, and the oxygen radical absorbance capacity (ORAC) in plasma were measured in 30 healthy nonpregnant, 14 normal pregnant, 9 women with pregnancy-induced hypertension (PIH), and 14 preeclamptic women. Pregnant participants were measured during pregnancy and after delivery.

Results: Women suffering from PIH and preeclampsia showed higher levels of the antioxidants vitamin E and uric acid, and lower levels of vitamin C compared with normal pregnant and nonpregnant women. All markers for oxidative stress were comparable between groups. Ethene levels showed a positive correlation with protein carbonyls but no correlation could be demonstrated with the free glutathione/oxidised glutathione ratio.

Conclusions: PIH and preeclampsia are associated with minor alterations in antioxidant levels without signs of oxidative stress. Detection of ethene in exhaled air seems a promising noninvasive method to study lipid peroxidation but further research in more severe preeclampsia is needed.