Aquaglyceroporins in normal and preeclamptic placentas

DAMIANO, A.; ZOTTA, E.; DEL MÓNACO, S.; IBARRA, C.

Mainz, Germany

Congreso; 9th Meeting of the International Federation of Placenta Associations and 10th Conference of the European Placenta Group; 2003

European Placenta Group

The syncytiotrophoblast of human term placenta (hST) is a continuous, multinucleated structure with minimal tight junctions. Consequently, the transport of metabolites, ions and water from mother to fetus should take place primarily via transcellular routes. Transcellular water flux may be facilitated by aquaporins. Previously, we have reported the expression in hST of aquaporin 3 (AQP3), aquaporin 7 (AQP7) and aquaporin 9 (AQP9) named aquaglyceroporins. These proteins allow the passage of water, urea and glycerol. AQP9 also permits the rapid passage of carbamides, polyols, purines and pyrimidines. We have observed that the expression of AQP9 is increased, AQP3 is decreased, and AQP7 is unchanged in hST from preeclamptic pregnancies. The aim of our work is to investigate the function of these water channels in hST from normal and pathological pregnancies. In order to evaluate the functionality of these aquaglyceroporins, explants from normal and preclamptic placentas were cultured in DMEM for 48 h. Unidirectional fluxes of 3H-mannitol and 14C-urea were measured. In normal placenta, we observed that the incorporation of 3H-mannitol was inhibited by HgCl2 0.3 mM. The uptake of 14C-urea was only inhibited by phloretin 0.5 mM. The uptake of 14C-urea in explants from preeclamptic placentas was also inhibited by phloretin 0.5 mM but its incorporation and inhibition were higher than in normal placentas. These results demonstrate that functional aquaglyceroporins are present in placental villous tissue culture from normal and preeclamptic pregnancies. Further experiments will be needed to elucidate the importance of these aquaglyceroporins in the etiology of preeclampsia.