Abstract
Summary
The mechanisms of zinc absorption and the effect of EDTA (ethylenediaminetetraacetic acid) on zinc absorption were studied at the intestinal digesta, intestinal mucosa, and blood plasma levels. Dialytic and gel nitration studies showed complexing of 65Zn with free amino acids or EDTA-14C in the intestinal digesta. The EDTA-14C:65Zn complex was bound to a zinc binding protein in the intestinal mucosa (mol wt 14,000-18,000) and to a plasma protein (mol wt 65,000-70,000), that had a greater affinity for zinc than the mucosal protein. The ratios obtained for the cpm EDTA-14C:cpm 65Zn in the main peaks eluted from gel filtration columns (1.10 in intestinal digesta preparation, 1.26 in mucosa soluble fractions, and 1.26 in blood plasma) indicated strong binding of the EDTA-zinc complex. When EDTA was not present in the diet, 65Zn complexed with amino acids in the intestinal digesta and with the same mucosal and blood proteins.
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