In Vitro Studies on the Absorption and Interactions of Zinc, Copper, Manganese and Iron in Rat

Abstract

Background: The exact details of the processes of trace metals absorption and interactions in the gastro intestinal tract remain uncertain. Absorption for the most part, takes places in the small intestine. The exact site of maximum absorption, as defined either by kinetic rate or quantity has not been clearly defined. Similarly, the luminal and cellular interactions of trace metals are not vividly known. Therefore, the present study was designed to throw more light on these two phenomena.

Objective: To examine the absorption and interactions of zinc, copper, manganese and iron in rat intestine.

Method: Everted duodenal and ileal gut sacs were prepared from adult male Wistar albino rats in the post absorptive state. The sacs were filled with 0.15M Tris-Krebs buffer, pH 7.3 free from the metals whose absorption and interactions were to be investigated until slightly distended. The uptake of Zn, Cu, Mn and Fe was studied at specific concentration ranges. Sacs were incubated for 30 minutes at 370C with continuous aeration in media containing the same buffer and different concentrations of metals. For the interaction studies, only duodenal sacs were used. All the sacs were incubated as for the absorption studies, Zn, Cu, Mn and Fe were introduced into the different media in pairs or singly for the controls at concentrations of 5.0mM, 9.0mM, 7.0mM and 6.0mM respectively.

Results: The absorption of Zn in the duodenum and ileum, Cu in the ileum and Fe in the duodenum were by a saturable carrier mediated process. The absorption of Cu in the duodenum, Fe in the ileum and Mn in both the duodenum and ileum were, most likely, by simple diffusion. As for the interaction experiments, Zn and Cu inhibited uptake of the other, as did Zn and Fe. Cu also depressed Mn uptake under the conditions used but not vice versa.

Conclusion: The absorption of trace metals occur equally well in the duodenum and ileum, and the interactions of metals studied may be of nutritional significance under normal conditions as well as in conditions of nutritional imbalance.


Keywords: Gut sac, Duodenum, Ileum, interaction, trace metals, absorption.

NQJHM Vol. 15 (3) 2005: pp. 110-114