Patricia Lanza de Moraes, Lucas M. Kangussu, Carlos Henrique Castro, Alvair P. Almeida, Robson A.S. Santos and Anderson J. Ferreira* Pages 869 - 875 ( 7 )
Background: Angiotensin(Ang)-(1-7) is a biologically active member of the reninangiotensin system that participates of the regulation of blood pressure. Although Ang-(1-7) is able to potentiate the vasodilator effect of bradykinin in coronary bed of rats, a direct vasodilator effect of Ang-(1-7) in this vascular bed has not been characterized.
Objectives: The aim of this study was to evaluate the mechanisms involved in the vasodilator effect of Ang-(1-7) in the vasculature of isolated rat hearts perfused according to the Langendorff technique at constant flow.
Methods: Isolated hearts, after approximately 30 minutes of stabilization, were perfused with Krebs-Ringer solution (KRS) alone (control) or KRS containing Ang-(1-7). The participation of the Ang-(1-7) receptor Mas, AT1 receptor, angiotensin-converting enzyme (ACE) and ACE2 was evaluated perfusing hearts with a combination of Ang-(1-7) plus A779, Ang-(1-7) plus losartan, Ang-(1-7) plus captopril/enalapril and Ang-(1-7) plus DX-600, respectively.
Results: Ang-(1-7) induced a significant decrease in the perfusion pressure, indicating a direct vasodilatation action of this peptide in the coronary bed. This effect was abolished by A779, captopril, enalapril and DX-600 an ACE2-specific inhibitor. However, AT1 blockade did not blunt the Ang-(1-7) effect. No significant changes were observed in heart rate, as well as in contractile tension and ±dT/dt. Moreover, immunohistochemical analysis showed the presence of Ang-(1-7) and Mas in coronary vessels.
Conclusion: The Ang-(1-7) concentration used in this study was unable to induce changes in the cardiac function since no consistent alterations in contraction force and HR were viewed after Ang- (1-7) perfusion. In summary, this study showed that Ang-(1-7) induces vasodilation in the coronary bed of rats and this effect involves coupling to Mas receptor and interaction with ACE and ACE2.
Angiotensin-(1-7), Mas receptor, Angiotensin-converting enzyme 2, heart, A779, AT1 receptor, Langendorff technique.
Departamento de Morfologia, Av. Antônio Carlos, 6627 – ICB – UFMG, 31 270-901 – Belo Horizonte, MG, Department Physiology and Biophysics, Biological Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Department of Physiological Sciences, Federal University of Goias, Goiania, Department Physiology and Biophysics, Biological Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Department Physiology and Biophysics, Biological Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Departamento de Morfologia, Av. Antônio Carlos, 6627 – ICB – UFMG, 31 270-901 – Belo Horizonte, MG