The effects of excess renal copper on kidney function in the diabetic rat

Fifteen male Sprague-Dawley rats (250 g - 300 g) were randomly divided into 5 control and 10 diabetic. Diabetes was induced by streptozotocin injection. Five diabetic rats were treated with penicillamine to chelate copper. All rats were anesthetized for renal clearance studies three weeks following streptozotocin injection. Inulin, sodium p-aminohippurate (PAH) and dextrose were infused i.v. and serial blood and urine samples collected for inulin, PAH and glucose analysis. Renal copper was determined following euthanasia. The glomerular filtration rate (GFR) and tubular maximum (Tm) for PAH and glucose were calculated. These values and the renal copper levels were compared between the three groups using the student's t-test. GFR and the Tm for PAH and glucose were increased in both diabetic groups as compared to the control group (p less than .05), but no difference was noted between the two diabetic groups. Renal copper levels were increased in the non-treated diabetic rats but not in the penicillamine-treated rats (p less than .01) indicating that penicillamine effectively removed copper from the diabetic kidney. The conclusion is that excess renal copper in the diabetic rat does not affect renal function in the early stages of diabetes.