Effect of Placental Hypoxia on the Plasma Membrane Ca-ATPase (PMCA) Activity and the Level of Lipid Peroxidation of Syncytiotrophoblast and Red Blood Cell Ghosts E. Borrego-Dı ´az, J.C. Rosales, T. Proverbio, A. Teppa-Garra ´n, R. Andaluz, C. Abad, R. Marı ´n, F. Proverbio * Laboratorio de Bioenerge ´tica Celular, Centro de Biofı ´sica y Bioquı ´mica, Instituto Venezolano de Investigaciones Cientı ´ficas (IVIC), AP 20632, Caracas 1020A, Venezuela Accepted 30 August 2007 Abstract Term placental villous fragments from normotensive pregnant women were incubated under hypoxia in order to induce lipid peroxidation of the placental plasma membranes and, consequently, to increase their release of lipid peroxide products into the incubation medium. The homog- enates of the villous fragments were assayed for plasma membrane Ca-ATPase (PMCA) activity and TBARS. The incubation medium, after placental hypoxia, was used to incubate intact red blood cells (RBCs) from normotensive pregnant women. Similarly, intact RBCs from nor- motensive pregnant women were incubated with deproteinized blood plasma from normotensive pregnant women and women with preeclamp- sia. In all the cases, red cell ghosts were prepared from the incubated cells and assayed for PMCA and TBARS. The incubation of placental villous fragments under hypoxia led to an increase in the TBARS and a significant reduction in the PMCA activity of their homogenates, as compared to those of villous fragments incubated under normoxia. The exposure of intact RBCs from normotensive pregnant women either to the incubation medium of placental hypoxia or to deproteinized blood plasma from women with preeclampsia, caused a rise of the TBARS and a diminution of PMCA activity of the red cell ghosts. Inside-out vesicles were also prepared from intact RBCs incubated with the medium where the placental hypoxia was carried out. These vesicles were assayed for active calcium transport. Pretreatment of RBCs with the incubation medium of placental hypoxia led to a lower active calcium transport as compared to that of inside-out vesicles from RBCs without any prein- cubation. These results are in agreement with the idea that the RBCs can be peroxidized when passing through a highly oxidized medium, such as the placental intervillous space from women with preeclampsia. The peroxidized RBCs would contribute then to the propagation of lipid peroxidation from the placenta to nearby and far away tissues. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Placenta; Hypoxia; PMCA; Lipid peroxidation; Syncytiotrophoblast; RBCs; Blood plasma 1. Introduction Pregnant women (7e10%) can be affected by preeclampsia; a disease characterized by vascular endothelial damage, hyper- tension, proteinuria, edema, generalized arteriolar vasospasm and a state of oxidative stress [1,2]. It is known that the oxidative stress occurs when the body’s antioxidant defenses are over- whelmed by the generation of reactive oxygen species (ROS). These ROS can promote lipid peroxidation and vascular endo- thelial damage, which are commonly related to preeclampsia [3,4]. In fact, the serum of the women with preeclampsia shows an increased level of lipid peroxidation by-products as com- pared to normotensive pregnant women [3,5]. The placenta ap- pears to be the principal source of ROS in the women with preeclampsia, but maternal leukocytes and the maternal endo- thelium are also likely contributors [6]. The contribution of * Corresponding author. Tel.: þ58212 5041395; fax: þ58212 5041093. E-mail address: fproverb@ivic.ve (F. Proverbio). 0143-4004/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.placenta.2007.08.006 Available online at www.sciencedirect.com Placenta 29 (2008) 44e50