The significance of transferrin for intestinal iron absorption

Journal Article · Tue Feb 01 04:00:00 EST 1983 · Blood; (United States)

OSTI ID:6221741

Huebers, H A; Huebers, E; Csiba, E; Rummel, W; Finch, C A

A mechanism is proposed by which apotransferrin is secreted from mucosal cells, loaded with iron in the intestinal lumen, and then the intact complex is taken into the cell. Within the cell, iron is released and transferred to the blood stream, whereas iron-free transferrin returns to the brush border to be recycled. Researchers have investigated this hypothesis by measuring intestinal absorption of radioiron and /sup 125/I-labeled plasma transferrin using tied-off gut segments in normal and iron-deficient rats. There was no absorption of diferric transferrin from the ileum, but high absorption from the duodenum and jejunum segments. Jejunal absorption occurred as a function of the dose offered and showed saturation kinetics. In normal animals, 4 micrograms of the 50 micrograms of transferrin iron was absorbed over 1 hr. In iron-deficient animals, mean values as high as 13 micrograms were observed. Radioiron content of the jejunal mucosa bore a linear relationship to the dose administered and was inversely proportional to the amount of iron entering the plasma. Recycling of transferrin was indicated by the presence of labeled apotransferrin in the lumen, first observed between 15 and 60 min after the injection of diferric transferrin. A high resistance of diferric and apotransferrin to proteolytic degradation within the gut lumen was demonstrated. Comparative studies with lactoferrin and ferritin disclosed poor availability of their iron for absorption. The small amount that was absorbed did not relate to the iron status of the recipient animal. These studies support the role of mucosal transferrin as a shuttle protein for iron absorption.

• Research Organization: Department of Medicine (Hematology Research), University of Washington, Seattle
• OSTI ID: 6221741
• Journal Information: Blood; (United States), Journal Name: Blood; (United States) Vol. 61:2; ISSN BLOOA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
BIOLOGICAL MATERIALS
BLOOD
BLOOD PLASMA
BODY FLUIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHROMATOGRAPHY
COMPARATIVE EVALUATIONS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
FUNCTIONS
GASTROINTESTINAL TRACT
GLOBULINS
GLOBULINS-BETA
HEMATOLOGY
INTERMEDIATE MASS NUCLEI
INTESTINAL ABSORPTION
IODINE 125
IODINE ISOTOPES
ION EXCHANGE CHROMATOGRAPHY
ION EXCHANGE MATERIALS
IRON
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MATERIALS
MEDICINE
MEMBRANES
METALLOPROTEINS
METALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RODENTS
SEPARATION PROCESSES
TRACER TECHNIQUES
TRANSFERRIN
TRANSITION ELEMENTS
UPTAKE
VERTEBRATES