Zinc, cadmium, and iron interactions during intestinal absorption in iron-deficient mice

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Abstract
Zn absorption from a test dose of 65ZnCl2 was increased in mice with a high capacity to absorb Fe induced by a low-Fe diet. When radiolabeled ZnCl2 in concentrations varying from 0.025-0.30 mM was perfused through open-ended duodenal loops of mice fed this diet, the proportion of Zn taken up from the lumen and transferred to the body was greater from lower than from higher doses. The addition of Fe to the perfusate inhibited Zn uptake and transfer, and Zn had a similar effect on Fe absorption. Cd, a potent inhibitor of Fe uptake in mice fed a low-Fe diet, impaired Zn uptake under these dietary conditions. Apparently in dietary-induced Fe deficiency there are analogous mucosal binding sites for the uptake of Fe and Zn. There also appear to be mutually exclusive binding sites for the absorption of these metals: radiolabeled Fe absorption from an intragastric test dose was enhanced in mice with a high capacity to absorb Fe produced by bleeding, whereas the absorption of Zn was not increased.