Changes of urinary angiotensinogen concentration and its association with urinary proteins in diabetic rats

It had been reported that angiotensinogen might be a marker for activation of renin-angiotensin system, which was associated with the development of diabetic nephropathy. The purpose of this study was to investigate the functional roles of AGT in DN in vitro.

Diabetic rat models were built by single intraperitoneal injection of streptozotocin. The diabetic rats were divided into three groups, two of the three groups were treated with different doses of losartan, the other diabetic group was as control and normal rats acted as healthy control. In a 12-week investigation, we detected the changes of AGT in all rats' blood and urine and the association between AGT concentration and RAS activation and urinary proteins were analyzed in this study.

The serum AGT of rats had no significant differences (P>0.05 for all). The urinary AGT of the diabetic rats was significantly different from the control group, moreover, the urinary AGT of the diabetic rats under different treatments was also obviously different (P<0.05 for all). Besides, the results of immunohistochemical assay indicated that AGT expression level was correlated with renal tissues damage. The level of AGT was positively associated with urinary protein (r=0.493, P<0.01) and negatively correlated with CCr (r=-0.474, P=0.007) and the dose of ARB (r=-0.575, P=0.001). Moreover, the dose of ARB was independently associated with urinary AGT (B=-2.963, P=0.024) in diabetic rats.

Urinary AGT may be a marker for the activation of local RAS in kidney and independently associated with ARB.