Bioavailability and the mechanisms of intestinal absorption of iron from ferrous ascorbate and ferric polymaltose in experimental animals
- Univ. of Cape Town Leukaemia Centre, Observatory (South Africa)
The comparative bioavailability from matching quantities of iron in the form of ferrous ascorbate or ferric polymaltose was defined in rats. Studies were carried out in the intact animals under basal conditions and also when requirements for this metal were either increased or decreased by manipulating stores or erythropoietic activity. No significant difference was found in the total quantity of iron absorbed from either salt or complex under any of these circumstances, suggesting that the mucosal mechanism regulating the overall process was common to both. However, the rate of transfer from the lumen into portal blood was distinctive, reaching a maximum with salt at 30 min compared to 24 h for the complex. To explore the possibility that iron from the two sources was initially handled by different subcellular pathways, the radiolabeled compounds were instilled into loops of bowel that had been isolated between ligatures in vivo. Enterocytes were harvested and fractionated, and incorporation into ferritin and transferrin was determined using RIA. From salt, iron appeared rapidly in duodenal but not ileal ferritin, whereas mucosal transferrin increased under conditions of stimulated absorption, suggesting that this protein may act as a shuttle for the metal. In contrast, iron from polymaltose showed a cumulative incorporation into duodenal ferritin over time that correlated with iron absorption, defined by the appearance of radiolabel in the serum and in the carcass; a similar pattern was demonstrable in ileal mucosal cells. Conversely, binding of iron to transferrin was minimal. No iron polymaltose was found within the mucosal cells. It is suggested that the low rate of iron transfer from this ferric complex may reflect its extracellular breakdown in the lumen of the gastrointestinal tract.
- OSTI ID:
- 6142789
- Journal Information:
- Experimental Hematology (Lawrence, Kansas); (USA), Journal Name: Experimental Hematology (Lawrence, Kansas); (USA) Vol. 18:10; ISSN EXHMA; ISSN 0301-472X
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ABSORPTION
ANIMALS
BIOASSAY
BIOLOGICAL AVAILABILITY
BIOLOGICAL PATHWAYS
COMPLEXES
DIAGNOSTIC TECHNIQUES
ELEMENTS
FERRITIN
GLOBULINS
GLOBULINS-BETA
IMMUNOASSAY
IMMUNOLOGY
INTESTINAL ABSORPTION
IRON
IRON COMPLEXES
IRON ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANES
METABOLISM
METALLOPROTEINS
METALS
MUCOUS MEMBRANES
ORGANIC COMPOUNDS
PROTEINS
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNODETECTION
RADIOIMMUNOLOGY
RATS
RODENTS
TRACER TECHNIQUES
TRANSFERRIN
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS
UPTAKE
VERTEBRATES