PLACENTAL TRANSFER OF 131I-LABELLED IODIDE IN THE GUINEA-PIG

Abstract
SUMMARY: The transfer of radioactive iodide (131I) across the guinea-pig placenta has been investigated, using an in situ perfusion technique. From these studies, it can be concluded that iodide is actively transported from the maternal side to the foetal side of the placenta, and is concentrated on the foetal side. Radio-iodide accumulates on the foetal side because the foetal placenta concentrates iodide from the maternal circulation and transfers little to the maternal circulation. High concentrations of stable iodide perfused on the foetal side did not affect the transfer of radio-iodide from the maternal circulation to the foetal side of the placenta. Sodium thiocyanate, on the other hand, blocked the concentration of iodide on the foetal side, and caused a small discharge of radio-iodide from the placenta.