CONICET | Buscador de Institutos y Recursos Humanos

Transport of water, solutes and electrolytes between mother and fetus is one of the most important functions of the human placenta. The syncytiotrophoblast is the site of exchange and since its syncytial nature the fetal and maternal transport should take place primarily via transcellular routes.It is well known that in some pathological conditions such as preeclampsia, the shallow trophoblast invasion and the poor remodelling of the maternal spiral arteries result in an insufficient uteroplacental oxygenation. However, the assumption that the placental changes are induced only by hypoxia may be simplistic. It has been proposed that intermittent placental perfusion secondary to deficient trophoblast invasion of the endometrial arteries leads to an ischemia-reperfusion [hypoxia-reoxygenation] type insult. This insult may modify the expression and/or the function of transport proteins and the placental pH homeostasis. It was reported that the Na+/H+ exchanger (NHE) is expressed in human placenta and may play a role in the maintenance of intercellular pH.Recently, we described that isoform 3 of NHE (NHE-3) was reduced in preeclamptic placentas. However, up to now placental NHE regulation remains unclear.The aim of our work was to establish if changes in oxygen concentration may alter NHE-3 expression in human placenta. Explants from normal placenta were cultured in normoxia, hypoxia, and in hypoxia/reoxygenation. Western blot analysis and immunohistochemistry were performed to study NHE-3 expression. We found that the expression of NHE-3 decreased when explants were cultivated under hypoxic conditions and the posterior reoxygenation treatment partially restored NHE-3 expression. In all cases, NHE-3 was located in the apical membranes and in citoplasmatic regions.These results suggest that changes in oxygen tension may modify NHE-3 expression in human placenta. Further studies are needed to evaluate if this changes correlate with NHE-3 activity.

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