Treatment with angiotensin-(1-9) alleviates the cardiomyopathy in streptozotocin-induced diabetic rats

Diabetic cardiomyopathy, a disorder of the heart muscle in diabetic patients, is one of the major causes of heart failure. We hypothesized that angiotensin-(1-9) [Ang-(1-9)] attenuates cardiomyopathy in streptozotocin (STZ)-induced diabetic rats. Rats were injected with a single intraperitoneal injection of STZ (55 mg/kg body weight) to induced diabetic cardiomyopathy. 4 weeks later, diabetic rats were treated with Ang-(1-9) (200 ng/kg/min), angiotensin type 2 receptor (AT2R) blocker PD123319 (100 ng/kg/min), or Mas antagonist A779 (100 ng/kg/min) for 4 weeks. Although Ang-(1-9) treatment did not affect blood glucose and insulin levels, it significantly attenuated cardiac hypertrophy, reduced cardiac fibrosis and improved ventricular function in STZ-induced diabetic rats. Ang-(1-9) treatment suppressed cardiac NADPH oxidase activity and reduced formation of reactive oxygen species. Ang-(1-9) suppressed NFκB activation and reduced myeloperoxidase (MPO) activity and mRNA levels of TNFα and IL-1β in hearts of diabetic rats. In addition, Ang-(1-9) treatment suppressed activity of ACE and reduced angiotensin II (Ang II) formation in hearts of diabetic rats. The beneficial effect of Ang-(1-9) was blunted by coadministration of PD123319 but not by coadministration of A779. Finally, it was found that Ang-(1-9) treatment could alleviate STZ-induced cardiomyopathy in a dose-dependent manner. In conclusions, Ang-(1-9) attenuates cardiac dysfunction in STZ-induced diabetic rats. The Ang-(1-9)/AT2R axis should be investigated as a novel target for treatment of type 1 diabetic cardiomyopathy.