EXPERIMENTAL AND CLINICAL STUDIES ON THE MECHANISM OF IRON ABSORPTION IN THE DUODENAL MUCOSA

Abstract

In order to elucidate the mechanism of iron absorption, stereomicroscopic studies of the duodenal mucosa, and histologic studies on the localization of iron, transferrin and ferritin in the duodenal mucosa using rats fed by iron-free diet in the animal experiments and the cases with iron deficiency anemia in the clinical experiments were performed . The following results were obtained ; 1) Stereo-microscopic findings of duodenal mucosa after administration of iron reflected well histologic findings . Therefore, stereo-microscopic observations were useful to evaluate the absorptive capacity of iron in the duodenal mucosa . 2) Localization of transferrin in the duodenal mucosa before administration of iron was different between controls and cases with iron deficiency anemia both in the animal and clinical experiments. Transferrin was scarcely found only in the capillaries in controls, while transferrin was identified in the absorptive cells as well as stroma and capillaries inthe cases with iron deficiency anemia. From these findings, it was assumed that absorptive cells in the duodenum were prepared to be able to absorb iron promptly in the cases with iron deficiency anemia. 3) In the animal experiments, it was presumed that iron may be absorbed by two steps from the results of movement of localization of iron and transferrin obtained by the change of passage of time. 4) Localization of transferrin was closely consistent with that of iron in the duodenal mucosa. 5) In the animal experiments, time of transfer of iron from intestinal lumen to capillaries through absorptive cells in the rats fed by iron free diet was more shortened than that in the control rats. 6) In the clinical experiments, ferritin was mainly found in the epithelial cells of Lieberkuhn's gland before administration of iron . Ferritin was strongly stained in the epithelial cells at the top of villi and macrophage as well as the epithelial cells of Lieberkuhn's gland after administration of iron. However, localization of ferritin was not different between the controls and the cases with iron deficiency anemia . Therefore, it was interpreted that significance of ferritin on iron absorption was relatively small. From those results mentioned above, it was clarified that transferrin may be closely related to iron absorption in the duodenal mucosa . Therefore, it was suggested that transferrin may play the promotive role as one of the carrier-like substances of iron in the route of transfer of iron from the intestinal lumen to the capillaries through absorptive cells.