MARGINAL COPPER-RESTRICTED DIETS PRODUCE ALTERED CARDIAC ULTRASTRUCTURE IN THE RAT

To determine if chronic ingestion of a diet containing a marginally lo w level of Cu could cause deleterious alterations in cardiac ultrastru cture, male offspring were nursed by dams fed a diet containing either 6.7 or 2.8 mg Cu/kg from midgestation through lactation before weanin g to the same diet, Conventional measures of Cu status, including grow th, relative heart weight, tissue concentrations of Cu, ceruloplasmin activity, and tissue activity of Cu,Zn-superoxide dismutase (SOD) were similar in both dietary treatment groups at 5.5 months of age. Howeve r, significant increases In the number and volume of lipid droplets an d an increased incidence of pathological abnormalities In mitochondria and basal laminae were observed in sections of hearts from rats chron ically fed the diet containing 2.8 mg/kg Cu. Reduction of the dietary level of Cu from 2.8 to 1.3 mg/kg from 4 to 5.5 months of age caused s ignificant reductions in the concentration of Cu in serum and liver, b ut Cu content, Cu,Zn-SOD activity, pathological scores, and morphometr ic parameters in hearts were not modified by the greater restriction o f dietary Cu in adult rats. This study suggests that abnormalities in cardiac ultrastructure occurred in rats chronically fed diets marginal ly low In Cu, despite minimal changes in conventional biochemical indi cators of Cu status.