AJP - Cell Physiology, Vol 252, Issue 5 C477-C482, Copyright © 1987 by American Physiological Society
Effect of iron chelators on placental uptake and transfer of iron in rat
C. T. Wong, H. J. McArdle and E. H. Morgan
The uptake of radiolabelled transferrin and iron by the rat placenta has
been studied using two approaches. The first involved injection of a
ferrous or ferric iron chelator followed by injection of label. Neither
chelator decreased the amount of labelled transferrin in the placenta after
2-h incubation and only bipyridine, a ferrous iron chelator, inhibited iron
transport to the fetus. Deferoxamine (DFO), a ferric iron chelator, had no
effect on iron transport to the fetus but reduced iron uptake by the liver.
Both bipyridine and DFO increased iron excretion into the gut and by the
urinary tract to the same degree into the gut, but there was a 10-fold
greater urinary excretion with bipyridine than with DFO. Injection of iron
attached to the chelators showed that neither bipyridine nor DFO could
donate iron to the fetus as efficiently as transferrin. The mechanism
involved was further investigated by studying the effect of the chelators
on uptake of transferrin-bound iron by placental cells in culture. DFO
inhibited iron accumulation more effectively than bipyridine in the
cultured cells. The effect was not due to a decrease in the cycling time of
the receptor. The results can be explained if the iron is released from the
transferrin in intracellular vesicles in the ferrous form, where it may be
chelated by bipyridine and prevented from passing to the fetus or converted
to the ferric form once it is inside the cell matrix.
