Incorporation of Iron from an Oral Dose into the Ferritin of the Duodenal Mucosa and the Liver of Normal and Iron-Deficient Rats

Abstract

To further characterize the role of ferritin in regulating iron absorption, uptake of an oral dose of 59Fe (0.2 mg Fe/kg body wt.) into duodenal and hepatic ferritin of control and iron-deficient (ID) rats was studied. Retention and uptake of 59Fe from Fe(II)-sulfate, Fe(III)-chloride, or Fe(III)-polymaltose were measured up to 28 h after dosing. Ferritin was determined by radioimmunoassay (RIA) and 59Fe ferritin-iron by gel electrophoresis. Retention and liver content of 59Fe was higher in ID rats than in controls. The mucosa of ID rats, however, retained only one third of the amount of 59Fe retained by the mucosa of controls. The mucosal and hepatic ferritin levels were lower in ID rats than in controls. The percentage of orally administered 59Fe found in the liver ferritin was therefore higher in control than in ID rats. However, when expressed as per unit of ferritin, iron uptake was eight times higher in ID rats. In contrast, mucosa ferritin of ID rats contained one-third of 59Fe per unit of ferritin than that of controls. Assuming no change in the mechanism of iron uptake into ferritin of control and ID rats, the differential uptake of oral iron into mucosa and liver ferritin indicates either a different compartmentation of the tissue ferritin or differences in the iron transport processes, but mucosal ferritin does not withdraw iron from intestinal absorption.

Rat Intestinal Iron Transfer Capacity and the Longitudinal Distribution of Its Adaptation to Iron Deficiency

“…1). The decrease in glucose trans fer in the distal 3 segments is in accordance with earlier observations [4], It is not accom panied by corresponding changes in iron transfer ( fig. 3).…”

“…In iron deficiency the increasing iron transfer capacity is inversely correlated to the mucosal content of ferritin and nonheme iron [2,4], Close correlations were also found between increases in intestinal iron transfer and in mucosal transferrin content regarding both, the quantitative aspect and the time course of these changes [32], Be cause of these correlations each of the three parameters had been considered to have an impact on the adaptation of intestinal iron transfer to the demand. More recently other substances have been proposed as ligands for iron in brush border membrane vesicles be cause of their iron binding properties, such as oleic and stearic acids [33] and a single 52,000-daiton protein [34], To evaluate the role of these compounds in intestinal iron transfer, more experimental evidence is needed.…”

“…In order to elucidate the mechanism by which the intestinal iron transfer capacity is adapted to the demand, the mucosal content of nonheme iron [1,2], ferritin [3,4], and transferrin [5,6] has repeatedly been com pared between iron-deficient and control an imals. All three parameters show adaptational changes which can be related to the adaptation of the intestinal iron transfer ca pacity.…”

Partial purification and characterization of ferritin from the liver and intestinal mucosa of chickens, turtledoves and mynahs

“…We have added rats to our study as a mammalian reference species. Comparisons of the present results with earlier studies provide corresponding values for the yield of ferritin protein in rat or mouse liver and mucosa (Cham et al ., 1985;Ehtechami et al ., 1989;Gérard et al ., 1996). In birds and some other species, only liver ferritin has been studied previously with a much lower yield than ours (10-fold to 100-fold) (Gonzalez del Barrio & Martin Mateo, 1983;Suryakala & Deshpande, 1999).…”