Copper metabolism and its interactions with dietary iron, zinc, tin and selenium in rats
1993
Yu, S.
This thesis describes various studies on copper metabolism and its interactions with selected dietary trace elements in rats. The rats were fed purified diets throughout. High intakes of iron or tin reduced copper concentrations in plasma, liver and kidneys. The dietary treatments also reduced biliary copper excretion through inhibition of intestinal copper absorption. When rats were fed on diets with moderately elevated iron and/or zinc concentrations, only copper concentrations in plasma were lowered. In essence, the combined effects of iron and zinc on plasma copper metabolism were additive. The ratio of copper:selenium in the diet determines the effect of copper intake on selenium metabolism. High intakes of copper decreased apparent selenium absorption and increased urinary selenium excretion in rats fed either low or normal amounts of selenium, but not in rats fed high-selenium diets. Raised dietary copper concentrations elevated selenium contents of liver and kidneys but slightly lowered that of spleen in rats fed a normal amount of selenium. Jaundiced rats with hereditary conjugated hyperbilirubinemia displayed a greater copper accumulation in liver after dietary copper challenge than did their normal counterparts. The aberrant response of the jaundiced rats was due to greater rates of intestinal copper absorption and lesser rise in biliary copper excretion when given a high-copper diet. Rats with hereditary analbuminemia had higher iron and copper concentrations in liver, kidneys and plasma when compared with their normal counterparts. Despite the absence of plasma albumin, the analbuminemic rats could maintain a relatively normal copper metabolism even after dietary copper or iron loading, suggesting that albumin in not crucial in copper transport from the intestine to the liver.
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