Copper Interference with the Intestinal Absorption of Zinc-65 by Rats

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Abstract
Earlier studies demonstrated that high levels of zinc interfered with 64Cu absorption and indicated that this interference was mediated at the intestinal level. The studies reported here were conducted to determine if the reverse were also true, that is, would copper depress 65Zn absorption and, if so, what was the site of the interference? The 65Zn was put into isolated duodenal segments and copper was administered either intraduodenally or intraperitoneally. When both copper and 65Zn were put into the ligated segment, subsequent absorption of 65Zn was depressed. When 65Zn was given intraduodenally and copper was given intraperitoneally, however, no depression in the subsequent absorption of 65Zn resulted. Copper concentrations in all of the sampled, nonintestinal tissues were as high or higher in the rats dosed intraperitoneally as in the rats dosed intraduodenally. This would indicate that copper did not depress 65Zn uptake by first building up to some “critical” level in nonintestinal tissues and subsequently blocking zinc absorption. Rather, the results of these experiments suggest that copper interference with 65Zn uptake was mediated at the intestinal level. These observations, and those reported previously, lead to the tentative conclusion that there is a mutual antagonism between zinc and copper during the absorption process and this antagonism apparently takes place either in or on the intestinal epithelium.