Influence of intraluminal constituents on zinc absorption by isolated, vascularly perfused rat intestine.

An isolated, vascularly perfused rat intestine system was utilized to compare the influence of a variety of potential zinc-binding compounds on zinc absorption. Citric acid, cysteine, reduced glutathione, histidine, methionine, picolinic acid and tryptophan were added to the lumen perfusate at 110 microM. Two lumen perfusate pH values (4.2 and 6.6) were compared. The influence of EDTA at pH 6.6 was also investigated as was the influence of citric acid, histidine, picolinic acid and tryptophan additions to the lumen perfusate at 550 microM. Of the substances tested only EDTA significantly enhanced the transfer of zinc from the lumen to the portal circulation. These results suggest these potential zinc chelators, exclusive of EDTA, do not promote zinc absorption by the intestine in this system.