Zinc, iron, copper, and magnesium concentrations in tissues of rats fed various amounts of zinc.

An experiment was conducted with rats to determine the effects on the tissue concentrations of Zn, Fe, Cu, and Mg of feeding various amounts of zinc. The rats were pair-fed one of the following diets for four weeks: Diet A, a zinc-deficient diet; a diet containing the recommended amoun of zinc (diet A plus 55 microgram of zinc per gram of diet), or diet A plus 550 microgram zinc per gram of diet. Concentrations of these elements in various tissues were determined by atomic absorption spectrometry after wet digestion. Feeding the rats zinc-supplemented diets resulted in increased zinc in blood, heart, kidney, and liver, and a marked decrease of iron in kidney and liver. Concentrations of the other two elements were unchanged in all tissues. Thus, the effect of zinc in decreasing iron concentrations in liver, observed by several investigators when rats were fed toxic amounts of zinc, also occurs when zinc is administered in normal or subtoxic amounts.