Renal function evolution in diabetic and aortic-constricted hypertensive rats

Diabetes and hypertension are frequently associated in humans and the patients run a higher risk of developing chronic renal failure. We combined streptozotocin-induced diabetes with a model of experimental renovascular hypertension induced by restricting aortic growth between the renal arteries. This model allowed us to have two kidneys in the same metabolic milieu; one exposed to hypertension and the other not. A moderate degree of hyperglycemia (2-4 g/l) was maintained with daily insulin. Determinations were made of urinary flow (UF) creatinine clearance (GFR), urinary protein excretion (UP), urinary glucose (UG), osmolality, and urinary electrolyte excretion. At the end of the study perfusion pressure (PP) and weight were measured in both the right and the left kidney in each group. All the kidneys were fixed and stained for microscopic observation. Functional study showed that urinary electrolyte excretion was higher in the diabetic group than in the control group from the first month. UF,UC and GFR were higher in the diabetic group than in the control group from the beginning of the study UP increased slightly in the control group along the study but the increase was much higher in the diabetic group. In both in the control and diabetic group, the right kidney was subject to a higher PP than the left one. Kidney weight was similar in the right and the left kidney in the control group but in the diabetic group it was higher in the right kidney than in the left and higher than in the control group in both kidneys. In the right of these results and the histology we conclude that diabetic animals develop renal damage to a greater extent than non-diabetic and this lesion occurs only in the hypertensive (right) kidney. These experiments show that both diabetes and hypertension are necessary for the development of glomerulosclerosis.