Epithelial sodium channel in the human syncytiotrophoblast. del Mónaco S., Assef Y., Damiano A.,

DEL MONACO S., ASSEF Y., DAMIANO A., ZOTTA E., IBARRA C., KOTSIAS BA

Santiago de Chile, Chile

Simposio; II Latinamerican Symposium on Fetal-Maternal Interaction and Placenta, and XIX Annual Meeting of The Chilean Society of Physiological Sciences (SSCHCF); 2005

Chilean Society of Physiological Sciences

The syncytiotrophoblast (SCT) of placenta regulates the transport of solutes and water between maternal and fetal blood. This transport involves movement of Na+ and its contribution to the osmotic pressure is an important determinant of the extracellular fluid volume. The aim of this work was to detect and characterize the Epithelial Sodium Channel (ENaC) in human SCT from normal and preeclamptic placentas. ENaC is associated with hypertensive disorders when its expression is deregulated in absorptive epithelia. Methods: We carried out studies using RTPCR, western blot and immunohistochemistry in normal and preeclamptic placenta. We also detected ENaC in the BeWo cell line (a human SCT model) and we studied the sodium currents generated in these cells with patch clamp. Results: alpha, beta and gamma-ENaC subunits are present in the apical membrane of the human SCT although alpha-ENaC subunit has a reduced expression in preeclamptic placentas. In BeWo cells, ENaC is modulated by aldosterone, vasopressin, estradiol and progesterone. Aldosterone (100 nM, 12 hs) induces a 20-fold increment in an AMPc-activated amiloride-sensitive current (p <0.05) with a reversal potential close to 3 mV and an inward conductance of 127 ± 26 pS/pF, values similar to those described in other human tissues with a variable expression of ENaC subunits. Conclusions: Although the role of EnaC in SCT is still poorly understood, the reduction in alpha-ENaC expression in preeclamptic placentas may have consequences for ion and water transport. Our data could be of help for future studies on the mechanism involved in the physiopathology of preeclampsia. Support: UBACYT ME044 & PRODIM (Argentina).