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

1. Selenate uptake by human placental brush-border-membrane vesicles was studied in order to establish whether this anion shares a pathway with sulphate. 2. Selenate uptake was found to be saturable with respect to medium selenate and was inhibited by the anion exchange inhibitor 4,4'-diisothiocyano-stilbene-2,2'-disulphonate (DIDS). 3. Anions which have a similar tetrahedral shape to selenate, e.g. chromate, molybdate, tungstate and sulphate, were effective inhibitors of selenate uptake when added to the incubation medium. 4. Sulphate inhibited selenate influx in a dose-dependent fashion; moreover sulphate was found to be a competitive inhibitor of selenate uptake. 5. It is concluded that selenate and sulphate share a pathway for transport in the human placental microvillus membrane.