Dietary copper and the net accumulation of liver and lung superoxide dismutase

Abstract

The effect of dietary copper deprivation on the net accumulation and functional activity of superoxide dismutase (SOD), a copper-containing enzyme, was studied in weanling and young adult Sprague-Dawley rats. Pregnant female Sprague-Dawley rats were fed diets based on spray-dried egg white that were sufficient (25 μg/g) or deficient (<1 μg/g) in copper. The dams were fed throughout gestation, parturition and lactation. One-half of the pups were then killed postnatally at day 20, or fed the same diets for an additional 20 days before termination. The livers and lungs were removed and frozen for eventual use in assays for SOD. SOD liver and lung enzymatic activity was reduced in copper-deficient rats to one-half normal. The mean plasma copper value for copper-deficient rats was 0.23 μg/mL, while the mean value for the control group was 1.1 μg/mL. The mean hematocrit values for copper-deficient and -sufficient rats were 23% and 43%, respectively. The body weights were not different at day 10 between the two groups, but by day 20 the body weights of copper-deficient rats were 82% of the weight of controls. Moreover, by day 40, the hearts of copper-deficient rats were 26% larger than those of control rats. With respect to SOD accumulation, copper status did not influence the amount of SOD in lung or liver, which was estimated using an enzyme-linked immunosorption assay. The amounts of SOD in both tissues, however, increased about 10-fold from day 20 to day 40.