POOL SIZE AND CONCENTRATION OF PLASMA-CHOLESTEROL ARE INCREASED AND TISSUE COPPER LEVELS ARE REDUCED DURING EARLY STAGES OF COPPER DEFICIENCY IN RATS

The progressive development of hypercholesterolemia, enlargement of plasma cholesterol pool size, and alteration in tissue mineral concentrations were determined during the early stages of copper deficiency. Fifty-four weanling male Sprague-Dawley rats were assigned to three dietary Cu treatments: deficient (0.6 mu g Cu/g diet), marginal (1.6 mu g Cu/g diet) and adequate (6.6 mu g Cu/g diet). Six rats from each treatment were killed after 3, 5 and 7 wk of dietary treatment. After only 3 wk of treatment, significantly lower hematocrits and liver Cu concentrations, as well as enlargements of plasma volume, plasma pool size of cholesterol and triacylglycerols and relative heart weight, were evident in rats fed the Cu-deficient and Cu-marginal diets relative to those fed the Cu-adequate diet. In general, these alterations were more pronounced in rats fed the Cu-deficient diet than in rats fed the Cu-marginal diet. Thereafter, the hematocrits and plasma volumes remained relatively constant, but the liver Cu concentration progressively decreased in rats in all treatments throughout the study. In contrast, the enlargements in plasma pool size of cholesterol and triacylglycerols relative to Cu-adequate rats were greater at the end of the study for the Cu-marginal and Cu-deficient rats. Most importantly, in the Cu-marginal rats, significantly greater plasma cholesterol and triacylglycerol pool sizes were detected earlier than were differences in concentrations. Thus, the present study established plasma cholesterol and triacylglycerol pool sizes as superior indices for the early detection of alterations in lipid metabolism in Cu deficiency.