Selenium (selenate) transport by human placental brush border membrane vesicles

Selenium is an essential trace element required by the fetus for normal growth, therefore knowledge on the placental transport of Se is important in the context of fetal nutrition. Recent work in this laboratory has shown that selenate is a competitive inhibitor of sulphate uptake by vesicles prepared from the brush-border membrane of the syncytiotrophoblast of the human term placenta (Shennan & Boyd, 1986). The brush-border membrane is the first barrier between the maternal and fetal circulations respectively. The interaction between selenate and sulphate strongly implies that they may share a pathway for transport in this membrane. Sulphate transport into human placental membrane vesicles is via a 4,4’-diisothiocyano-stilbene-2,2’-disulphonate (D1DS)-sensitive, sodiumindependent system which may represent an anion exchange pathway (Cole, 1984; Boyd & Shennan, 1986a, 6) . The purpose of the present study was to investigate directly the transport of selenate by human placental microvillus membrane vesicles in order to establish whether this anion does indeed share a pathway with sulphate. Thus the effect of the anion exchange inhibitor DIDS and divalent anions (in particular sulphate) was tested on selenate uptake.