UPTAKE OF CIRCULATING IRON BY DUODENUM OF NORMAL MICE AND MICE WITH ALTERED IRON STORES, INCLUDING SEX-LINKED ANEMIA - HIGH-RESOLUTION AUTORADIOGRAPHIC STUDY

  • 1 January 1976
    • journal article
    • research article
    • Vol. 34  (6) , 611-615
Abstract
Using EM radioautography, the deposition of i.v. administered Fe in the duodenal epithelium was studied in normal mice, Fe-overloaded and Fe-deficient mice and in mice with X-linked anemia (gene symbol sla) 4 and 24 h after injection of 59Fe. The resolution of radioautography with 59Fe was determined with a line source, and the distance from the hot line within which 1/2 of the grains fell (HD value) was 1650 .ANG.. In normal, Fe-overloaded and sla mice, radioiron was localized in the unidfferentiated crypt cells at 4 h and in the absorptive cells of the luminal half of the villi at 24 h. At both times the vast majority of the grains was seen over the areas rich in free ribosomes and rough endoplasmic reticulum. In Fe-deficient mice grains were not found at either time. The amount of Fe incorporated in the crypt cells was related to the size of the body Fe stores. The amount of Fe incorporated in the crypt cells may be the result of interaction between uptake and return to the blood of the circulating Fe. Once the crypt cells have differentiated into absorptive cells, the uptake and recirculation of Fe from and to the blood would cease, leaving an amount of message Fe which determines the absorptive cell''s subsequent capacity for Fe transfer to the plasma. In sla mice, in spite of tissue Fe deficiency, the amount of Fe deposited was similar to that of normal mice and markedly increased after treatment of the anemia. The accumulation of Fe in the crypt cells may result from the decreased return to the blood of the incorporated circulating Fe, due to the postulated deficient Fe carrier mechanism in sla, or may be a consequence of increased avidity of the absorptive cells for circulating Fe. In either event the absorptive cell receives an inappropriate message with resulting inappropriate absorption of Fe.

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