An Oral Formulation of Angiotensin-(1-7) Produces Cardioprotective Effects in Infarcted and Isoproterenol-Treated Rats

In this study we evaluated the cardiac effects of a pharmaceutical formulation developed by including angiotensin (Ang)-(1-7) in hydroxypropyl beta-cyclodextrin (HP beta CD), in normal, infarcted, and isoproterenol-treated rats. Myocardial infarction was produced by left coronary artery occlusion. Isoproterenol (2 mg/kg, IP) was administered daily for 7 days. Oral administration of HP beta CD/Ang-(1-7) started immediately before infarction or associated with the first dose of isoproterenol. After 7 days of treatment, the rats were euthanized, and the Langendorff technique was used to analyze cardiac function. In addition, heart function was chronically (15, 30, 50 days) analyzed by echocardiography. Cardiac sections were stained with hematoxylin/eosin and Masson trichrome to evaluate cardiac hypertrophy and damage, respectively. Pharmacokinetic studies showed that oral HP beta CD/Ang-(1-7) administration significantly increased Ang-(1-7) on plasma whereas with the free peptide it was without effect. Oral administration of HP beta CD/Ang-(1-7) (30 mu g/kg) significantly reduced the deleterious effects induced by myocardial infarction on systolic and diastolic tension, +/- dT/dt, perfusion pressure, and heart rate. Strikingly, a 50% reduction of the infarcted area was observed in HP beta CD/Ang-(1-7)-treated rats. Furthermore, HP beta CD/Ang-(1-7) attenuated the heart function impairment and cardiac remodeling induced by isoproterenol. In infarcted rats chronically treated with HP beta CD/Ang-(1-7), the reduction of ejection fraction and fractional shorting and the increase in systolic and diastolic left ventricular volumes observed in infarcted rats were attenuated. Altogether, these findings further confirm the cardioprotective effects of Ang-(1-7). More importantly, our data indicate that the HP beta CD/Ang-(1-7) is a feasible formulation for oral administration of Ang-(1-7), which can be used as a cardioprotective drug. (Hypertension. 2011; 57: 477-483.). Online Data Supplement