Renin and angiotensinogen gene expression in experimental diabetes mellitus

The renin-angiotensin system may play a role in the initiation and progression of diabetic kidney disease. In this study, the local intrarenal renin-angiotensin system was examined in streptozotocin-treated rats maintained moderately hyperglycemic by daily low-dose insulin injection. Four weeks after induction of diabetes, plasma renin activity was significantly lower in the diabetic compared to a non-diabetic control group (diabetes: 2.30 +/- 0.30 vs. control: 6.93 +/- 1.36 ng Al/ml/hr; P less than 0.01). Renal tissue renin content (diabetes: 1.81 +/- 0.46 vs. control: 2.05 +/- 0.27 micrograms Al/mg protein/hr; P less than 0.05) and renal renin mRNA (diabetes: 2.32 +/- 0.16 vs. control: 1.89 +/- 0.12 pg/micrograms RNA; P = NS) were not different between diabetic and control rats. Renal and liver angiotensinogen mRNA were lower in the diabetic group. Glomerular renin mRNA was not different between the diabetic and sham group. The dissociation between systemic renin activity (a decrease), and in renal renin content or mRNA in the diabetic rats (no change), suggests a post-translational alteration in renin processing and/or renin secretion.