Mucosal transferrin and ferritin factors in the regulation of iron absorption

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Abstract
Summary 1. A standardized decompensation and recompensation of iron homeostasis has been produced by a change-over from normal to iron deficiency and back. 2. Under these conditions the59Fe uptake into transferrin and ferritin of the mucosal “cytosol” and SDS treated “membrane” fraction has been measured together with the59Fe amount transferred into the body. 3. The increase of the intestinal59Fe absorption due to a progressive iron deficiency is associated with an increase of the59Fe uptake into the mucosal transferrin of the “cytosol” and the “membrane” fraction; the reverse is observed with regard to mucosal ferritin. 4. Three days after the re-establishment of normal conditions the59Fe absorption was lowered to normal values, while the59Fe uptake into mucosal ferritin achieved again normally high values. 5. The high apparent rate of absorption in iron deficient animals decreased during the last 50 min after injection of the59Fe labelled test dose. The59Fe content in the ferritin fraction increased simultaneously, whereas the59Fe content in the transferrin fraction remained the same. 6. The conclusion is drawn that the intestinal iron absorption is regulated by both mucosal iron binding proteins. Mucosal transferrin is responsible for the increase of absorption in iron deficiency while mucosal ferritin is responsible for the inhibition of iron absorption when the iron homeostasis recompensats.