Does Angiotensin (1-7) Contribute to the Antiproteinuric Effect of ACE-inhibitors?

Angiotensin-converting enzyme inhibitors (ACE-I) reduce proteinuria and protect the kidney in proteinuric renal disease. During ACE-I therapy, circulating levels of angiotensin (1-7) [Ang (1-7)] are increased. As cardiac and renal protective effects of Ang (1-7) have been reported, we questioned whether Ang (1-7) contributes to the anti-proteinuric effects of ACE-I treatment. Therefore, we evaluated whether Ang (1-7) infusion reduces proteinuria in a rat model of adriamycin-induced renal disease. In addition, the effect of a selective Ang (1-7) blocker, [D-Ala7]-Ang (1-7) (A779), was investigated in rats treated with the ACE-I, lisinopril (LIS). Six weeks after induction of proteinuria, therapy was started in four different groups: control, Ang (1-7), LIS, and LIS+A779. After two weeks, the rats were sacrificed. Six weeks after injection of adriamycin, the rats had developed proteinuria of 323+/-40 mg/24 hours. The proteinuria remained stable in the control group and in the Ang (1-7) group, but was reduced in both LIS and LIS+A779-treated groups. Similarly, blood pressure (BP) was unchanged in the control and the Ang (1-7) groups, but reduced in both the LIS and the LIS+A779 groups. Plasma levels of Ang (1-7) were increased in the Ang (1-7) and in both LIS-treated groups. We conclude that systemic Ang (1-7) plays no major role in the anti-proteinuric and BPlowering effects of ACE-I in this rat model of adriamycin-induced nephrosis.