Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2001
Publication Date: 3/20/2002
Citation: Saari, J.T. 2002. Kidney copper as an index of altered copper status in marginally-deficient rats [abstract]. The Federation of American Societies for Experimental Biology Journal. 16:A990.
Technical Abstract: Marginal copper (Cu) deficiency is difficult to study, in part because its effects may be small, but also because feeding of a deficient diet may not cause a discernable change in Cu status. The key to resolution of effects may be in the choice of Cu status index. In this study, liver Cu concentration, a commonly used index of Cu status, was compared with activity of ceruloplasmin (CP), a circulating Cu-dependent enzyme, and kidney Cu concentration for their utility in resolving effects of marginal Cu deficiency. Seventy male, weanling rats were fed diets containing, nominally, 0, 1.5, 3, 4.5 or 6 mg Cu/g of diet for 5 weeks. All three indices showed strong depression with severe deficiency (dietary Cu=0), but were relatively weak in their ability to distinguish between animals fed marginally deficient diets when compared by group statistics (ANOVA). Further, group statistics revealed no effect of marginal deficiency on six other variables known to change with severe Cu deficiency: heart weight/body weight, hematocrit, red cell distribution width, neutrophil count, glycated hemoglobin and platelet count. To take into account inter- animal variation, the three putative indices were plotted against these six variables and linear regression was performed on points representing marginally-deficient rats. None of the variables showed significant regression with liver Cu or serum ceruloplasmin, but three showed significant regression with kidney Cu. These findings indicate that kidney Cu is preferable to liver Cu or ceruloplasmin as an index of Cu status in marginal deficiency and that linear regression is a possible way of testing for effects of changes in Cu status, especially when effects are subtle.