PLACENTAL TRANSFER OF IRON IN THE GUINEA PIG

Abstract

The uptake of transferrin and iron by the placenta and iron transfer to the fetuses were studied in the guinea pig using radioiodine labelled guinea pig transferrin and albumin and 59 Fe. The amount of labelled transferrin bound by the placenta increased during the first 30 min after injection, then reached steady levels which were maintained for the next 60 min. No labelled transferrin or albumin was detected in the fetal blood. The rate of transfer of iron from maternal plasma to the fetuses increased after the 25th day of pregnancy to reach a maximum at about the 54th day, and then decreased markedly by the 65th day. The effects of hypoxia and of metabolic inhibitors on iron transfer were studied by in vivo perfusion of the placenta. Reduction in 59 Fe transfer was observed in animals breathing 10 or 15% oxygen in nitrogen, or when sodium arsenite (5 mM), sodium cyanide (10 mM) or 2,4‐dinitrophenol (10 mM) were added to the perfusate. The results indicate that maternal plasma transferrin is an adequate source of iron for the fetal guinea pig, and that placental transfer of iron is an active process, dependent on cellular metabolism, in which maternal plasma transferrin is taken up by the placenta followed by removal of the iron from the transferrin and transfer to the fetal blood.