Abstract: Type I diabetes mellitus were made in Wistar rats by intravenous injection of 35 mg/kg streptozotocin freshly dissolved in citrate-buffered saline solution. Stable moderate hyperglycemia was maintained throughout the duration of the experiment,without receiving any insulin injection. Body weights were markedly reduced at 1 week after induction of the diabetes and maintained throughout the experiment in the untreated diabetic rats，whereas non-diabetic control rats gained weight during the 5-month follow-up. Blood pressure （BP） and renal function data at 5 months after induction of diabetes were summarized.The untreated uninephrectomized diabetic rats developed hypertension with mean arterial pressure （MAP） of 128±2 mmHg under anesthesia. Renal vascular resistance （RVR） was markedly elevated·in the untreated diabetic rats as compared to that in controls （P＜0.001），leading to a significant lower renal plasma flow （RPF）（P＜0.01）.Glomerular filtration rate （GFR） was comparable between untreated diabetic rats and controls.Thus,Filtration fraction （FF） rose significantly （P＜0.001）.Urine flow rate was also markedly increased in the untreated diabetic rats.Un-treated diabetic rats showed a significant increase in urinary protein excretion as early as 4 weeks after induction of the disease （36.8±3.6 vs. 21. 5±1.7,P＜0.01 in control rats at week 4） , with a substantial progressive increase of this value over time. A ratio of the heart weight to the body weight was 3. 5±0.1 to 2.4±0.1 （P＜0.001） and the left kidney weight to the body weight was 9.9±0.7 to 3. 9±0.1 （P＜0.001）.Both ra-tios were markedly higher in untreated diabetic rats as compared to those in controls. Thus, the STZ-injected uninephrectomized rats developed overt diabetic nephropathy,as evidenced by the development of hypertension,progressive proteinuria and renal dys-function.

Key words: Wistar rats, Type I diabetes mellitus, Nephropathy, Hyperglycemia, Urinary protein