Differential absorption of zinc and low-molecular-weight ligands in the rat gut in protein-energy malnutrition.

The differences in zinc absorption in the presence of four low-molecular-weight ligands in the jejunum, ileum and colon of protein-energy malnourished juvenile rats (M), and their controls (C) were investigated. An in vivo perfusion procedure was applied to vascularly intact segments of the three areas of the gut. The absorption of L-proline and L-histidine, and a hydrolysis-resistant dipeptide, glycylsarcosine, were also determined. In certain instances, the M rats absorbed zinc at a lower rate than the C animals. This effect was especially consistent throughout the gut when glycylsarcosine was present in the perfusates. In the colon, zinc, but not the amino acids, was taken up. Glycylsarcosine was well absorbed by the colon in both the M and C rats. The data indicate that protein-energy deficiency may impair the absorption of zinc by the rat intestinal mucosa in the presence of low-molecular-weight substances of high affinity for zinc, without altering the absorption of amino acids, or of zinc organometallic complexes in which the metal is tightly bound. The two contrasting situations may be relevant to alleviating zinc deficiency in nutritionally compromised conditions.