NUTRITION RESEARCH, Vol. 9, pp. 1161-1166, 1989 0271-5317/89 $3.00 + .00 Printed in the USA. Copyright (c) 1989 Pergamon Press plc. All rights reserved. DIETARY COPPERAND THE NET ACCUMULATIONOF LIVER AND LUNG SUPEROXIDE DISMUTASE David Dat Tran, Nadia Romero, Donald Tinker, Ph.D. and Robert Rucker, Ph.D. I Department of Nutrition, University of California, Davis, CA 95616 ABSTRACT The effect of dietary copper deprivation on the net accumula- tion 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 ~g/g) or deficient (< I ~g/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 pg/mL, while the mean value for the control group was I.I pg/mL. The mean hematocrit values for copper-deficient and -sufficient rats were 23% and 43%, respectively. The body weights were not different at day ]0 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 immuno- sorption assay. The amounts of SOD in both tissues, however, in- creased about lO-fold from day 20 to day 40. KEY WORDS: Superoxide dismutase, copper, lung development INTRODUCTION The role that cofactors play in modulating the expression and net accumu- lation of proteins and enzymes is an important area of nutritional investiga- tion. Previously it was reported that dietary copper deficiency in young adult rats resulted in a decrease in liver superoxide dismutase (SOD) activity, but not a decrease in the net accumulation of SOD (I). Herein, we have re-examined this relationship during a period of rapid growth. It seemed likely that SOD might be more sensitive to perturbation during periods of rapid growth. Fur- thermore, we have examined SOD in lung, an organ that is particularly dependent upon normal maintenance of SOD activity. SOD activity in lung is responsive to a number of stimuli and nutritional conditions (2-9), e.g., oxidants and 1Corresponding author. 1161