The cadmium effect on iron absorption.

Test solutions of cadmium and labeled iron salts, soluble complexes of diferric transferrin, or hemoglobin iron were introduced orally or were injected into tied-off jejunal segments in rat. Cadmium reduced the absorption of iron salts to about half in both normal and iron-deficient rats. Hemoglobin iron absorption was enhanced, indicating that the processing of this form or iron and its release from mucosa to blood was intact. A greater reduction in iron absorption occurred in iron-deficient rats when transferrin iron was injected into gut loops. Mucosal radioiron content in animals given cadmium with either iron salts or transferrin iron was increased. The primary effect of cadmium was on intracellular processing of iron salts and transferrin iron. The major portion of cadmium taken up by the mucosa of normal animals was bound to ferritin, and the effect of cadmium within the mucosal cell may be reduced thus.