ROS and RNS include a wide range of intermediates such as superoxide anions (O2·-), H2O2, hydroxyl radicals (OH.), NO, and peroxynitrite anion (ONOO−). These molecules are mediators of the immune response (reviewed in [64]) and are important signaling molecules involved in many physiological processes including cell differentiation [75], VX-770 chemical structure proliferation [9], migration and adhesion [101], and apoptosis [41, 57]. However, excessive amounts of these prooxidants can lead to cellular dysfunction as well as damage through interaction with lipids, proteins, and DNA. Placental ischemia/hypoxia stimulates the release of many factors into the

maternal circulation which in turn induces excessive inflammation and an increased oxidative environment. The generation of superoxide within the endothelium via the stimulation of NAD(P)H oxidase is believed to play a critical role in vascular dysfunction associated with preeclampsia. Superoxide can scavenge NO, thereby generating peroxynitrite, which contributes to increased oxidative stress and may cause endothelial dysfunction by promoting the formation of vasoconstrictors such as ET-1 while inhibiting the synthesis of vasodilators such as prostacyclin (reviewed in [123]). In the maternal vasculature, an increase in eNOS and markers for peroxynitrite have been identified, along with a decrease in the antioxidant superoxide dismutase [118]. Elevated

levels of oxidized LDL (oxLDL) and its scavenger receptor, LOX-1, have also been identified in arteries of women with preeclampsia, where they likely 3-MA solubility dmso promote the formation of superoxide and peroxynitrite [125].

Furthermore, increases in arginase, an enzyme which competes for substrate with NOS [124], and circulating ADMA, an endogenous inhibitor of eNOS [115, 126], have been found in women with preeclampsia. Both arginase and AMDA may result in eNOS uncoupling, contributing to oxidative stress by reducing the production of NO and promoting the production of superoxide. The vascular effects of preeclampsia are profound. While normal pregnancy is associated with reduced vascular Succinyl-CoA resistance, alleviating cardiovascular stress associated with increased blood volume, preeclamptic mothers experience an increase in cardiac output, stroke volume, and systemic vascular resistance [38]. Thus, elevated blood pressure is a defining characteristic of preeclampsia. However, increased vascular resistance occurs in all organs; for example, there is evidence of reduced peripheral blood flow in the calf of women both before and after clinical manifestations of preeclampsia, [7, 8]. Disturbances in uterine, opthalmic, and brachial blood flow have also been noted [139]. The endothelium is central to the altered hemodynamic response observed in preeclampsia. Markers of endothelial activation, including thrombomodulin, von Willebrand factor, fibronectin, and Pai-1 are increased in the plasma of women with preeclampsia [37, 127].