THE DISTRIBUTION OF PARENTERAL IRON HAEMATINICS IN NONPREGNANT, PREGNANT AND LACTATING RATS.

The distribution of (59)Fe has been investigated in nonpregnant, pregnant and lactating rats and their young after injection of solutions containing a high molecular weight iron-dextrin complex (iron-dextrin, intravenously), and a low molecular weight complex of iron, sorbitol and citric acid (iron-sorbitol, intramuscularly), each labelled with (59)Fe. At different times after injection of a dose corresponding to 1.5 mg of iron per kg of body weight, the quantity of (59)Fe was determined in different organs, urine and carcass, and for pregnant rats also in foetuses and placentas. In some investigations, distribution in the foetuses was also studied. Iron-dextrin was localized mostly in the livers of both pregnant and nonpregnant rats; (59)Fe was then redistributed from this organ and incorporated into the erythrocytes. In pregnant rats, redistribution was accompanied by a placental transfer, the degree of incorporation into the erythrocytes of the mother being diminished. About 30% of the iron-sorbitol was excreted in the urine, while the remainder was distributed throughout the whole organism. Incorporation into the erythrocytes and placental transfer began earlier with iron-sorbitol than with iron-dextrin. At 14 days from injection into nonpregnant rats, however, the degree of incorporation into the erythrocytes of iron from the two complexes was identical. The rate at which incorporation of (59)Fe occurred into the erythrocytes was the same for the two preparations. The degree of incorporation into the erythrocytes after injection of iron-sorbitol into pregnant rats diminished in the same pattern as for iron-dextrin. Investigations into the mechanism of the placental transfer of iron-sorbitol from mother to foetus suggested that this is essentially an active process.