COPPER DEFICIENCY INCREASES THE SUSCEPTIBILITY OF LIPOPROTEINS AND TISSUES TO PEROXIDATION IN RATS

Male Wistar rats were pair-fed from weaning for 6 wk either a copper-d eficient diet or a control diet containing sucrose. Hypercholesterolem ia in copper-deficient animals was associated with a significantly gre ater plasma apolipoprotein B concentration and modifications in the li pid composition of triglyceride-rich lipoproteins containing apolipopr otein B. The proportion of triglycerides was elevated and the proporti on of cholesterol was reduced in the VLDL + LDL fractions from copper- deficient rats compared with control animals. When the VLDL + LDL frac tions were subjected to in vitro copper-induced oxidation, the lipopro tein fractions from copper-deficient rats were more susceptible to oxi dative damage than lipoprotein fractions from control rats as indicate d by the rate of diene conjugation. Hydroperoxide and thiobarbituric a cid-reactive substance (TBARS) measurements performed 3 h after the in duction of peroxidation were in agreement with the greater formation o f conjugated dienes. Concentrations of TBARS were significantly greate r in heart homogenates from copper-deficient rats compared with contro l rats. After exposure of tissue homogenates to iron-induced lipid per oxidation, TBARS were significantly higher in liver and heart from cop per-deficient rats compared with control rats. Of particular importanc e is the observation that copper deficiency has a harmful effect on li pid peroxidation in the cardiovascular system.