Aquaglyceroporins in human placenta

DAMIANO ALICIA E; ZOTTA ELSA; IBARRA CRISTINA

San Pablo

Simposio; I Latin-American Symposium on Maternal-Fetal Interaction and Placenta:Basic & Clinical Research; 2003

Placenta Association of the Americas- Grupo Latinoamericano de placenta

The syncytiotrophoblast of human term placenta is a continuous multinucleated structure with minimal tight junctions, which results from the fusion of the underlying cytotrophoblast cells. Thus, the transport of metabolites, ions and water from mother to fetus should take place primarily via transcelular routes. Transcellular water flux across placental membranes may be facilitated by aquaporins (AQPs), membrane proteins functioning as water channels that are widely expressed in cells and tissues. We have recently reported the expression and localization of AQP3, AQP7 and AQP9 in human normal placenta. These water channels belong to the subfamily of aquaglyceroporins, which permeate water and small solutes. We have observed by western blot and immunohistochemistry that AQP3 and AQP9 expression is altered in pathological conditions including those associated with abnormal fetal growth such as intrauterine growth retardation and preeclamptic pregnancies. In preeclamptic placenta, AQP9 protein expression was increased, AQP3 was decreased while AQP7 was unchanged. To characterize their function we have used the BeWo cell line as a human trophoblast model. At light microscopy, it was observed that these cells form confluent monolayers on permeable support in 3-5 days in culture. AQPs function was determinated by measuring the water osmotic permeability (Posm) across the monolayer in an Ussing chamber at different times and before and after addition of HgCl2, a known AQP inhibitor. Our results indicate that the expression of these aquaglyceroporins in hST may play an important functional role in fluid transport from mother to fetus and that could be altered in pathological conditions.