Urinary excretion of albumin and total protein in normal and streptozotocin diabetic rats

Abstract

Abstract. Using a radioimmunoassay the urinary albumin excretion rate has been measured in groups of streptozotocin diabetic female Wistar rats and non-diabetic control rats. Total protein excretion has been measured with the Biuret technieque in the same animals. One group of 4 rats was given 35 mg streptozotocin iv. The rats remained non-ketotic and were not treated with insulin. The geometric mean albumin excretion before the induction of diabetes was 0.38 mg/24 h. For the next 4 days after streptozotocin the albumin excretion was not significantly increased. From day 16 to day 30 the mean albumin excretion was 2.4 mg/24 h, which is a significant increase from the initial value (2 P = 0.0082). Another group of 8 rats showed ketonuria on the second day after the injection of 100 mg streptozotocin iv, and they were treated with insulin daily. Geometric mean albumin excretion before the induction of diabetes was 0.38 mg/24 h, and the next 4 days after the induction of diabetes it was not significantly increased. During the period from day 16 to day 30 a small, but significant, increase to 0.76 mg/24 h (2 P = 0.029) occurred when compared to prevalues. Total protein excretion showed a significant increase in both diabetic groups just after the streptozotocin injection. In a long-term study albumin excretion was measured every month up to the age of 12 months in 8 insulin treated rats. The results obtained in this group have been compared to that of a non-diabetic control group. Both groups showed a steady increase in albumin excretion. However, the slope of the curves was significantly steeper in the diabetic rats (2 P = 0.0000095).