Plasma Iron and Saturation of Plasma Iron-binding Protein in Dogs as Related to the Gastrointestinal Absorption of Radioiron

The absorption of a test amount of radioactive iron during artificial saturation of the plasma iron-binding protein, by the repeated intravenous injection of small amounts of iron, was measured in three normal and four anemic dogs. The procedure had no detectable influence on the iron absorption of the normal dogs nor on that of two of the anemic dogs. Two other anemic dogs showed some suppression of iron absorption, though the amount absorbed was still in excess of that absorbed by a normal dog. The reasons for this suppression are not clear from these experiments. Artificially raising the plasma iron to normal levels in one anemic dog did not influence the absorption of iron from the gastrointestinal tract nor was a delayed effect noted after the plasma iron had fallen to base line levels after 5 hours of artificial saturation. It appears that the plasma iron-binding protein and its relative saturation play little role per se in the control of iron absorption in dogs.