(Hypertension. 1997;30:549.)
© 1997 American Heart Association, Inc.
Articles |
Role of Angiotensin-(1-7) in the Modulation of the Baroreflex in Renovascular Hypertensive Rats
From the Laboratório de Hipertensão, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Correspondence to M.J. Campagnole-Santos, Departamento de Fisiologia e Biofísica, Av Antonio Carlos, 6627-ICB-UFMG, 31270-901, Belo Horizonte, MG, Brazil. E-mail marrob{at}oraculo.lcc.ufmg.br
Abstract In this study, we evaluated the effect produced by lateral ventricle (intracerebroventricular, ICV) infusion of the selective angiotensin (Ang)-(1-7) antagonist, D-Ala7-Ang-(1-7) (A-779), in the modulation of the baroreflex control of heart rate in two-kidney, one clip renovascular hypertensive rats (2K1C) treated with the angiotensin-converting enzyme (ACE) inhibitor enalapril. Twenty days after the surgery to produce renovascular hypertension, ICV cannulas were implanted in the rats with blood pressure (BP) greater than 145 mm Hg (n=33) and in sham-operated rats (n=32). Five days later, the rats were treated with enalapril (10 mg · kg-1 · d-1; 6 days, in the drinking water) or vehicle (tap water). On the sixth day of treatment, direct continuous BP recording and measurement of reflex changes in heart rate elicited by phenylephrine were made in conscious rats before and at 1 hour of ICV infusion of saline (8 µL/h) or A-779 (4 µg/h). To evaluate the degree of ACE blockade produced by enalapril treatment, the pressor effect of Ang I (50 ng, IV, and 100 ng, ICV) and plasma ACE activity was determined. As expected, enalapril treatment in 2K1C produced a significant fall in BP, significant attenuation in the pressor response of Ang I (IV), and a reduction in plasma ACE activity. In addition, enalapril treatment increased the baroreflex sensitivity (0.76±0.04 versus 0.43±0.04 ms/mm Hg in 2K1C untreated rats). ICV infusion of A-779 reverted the improvement in baroreflex sensitivity produced by enalapril treatment in 2K1C (from 0.80±0.07 to 0.42±0.08 ms/mm Hg) and also attenuated the baroreflex sensitivity in untreated 2K1C (0.36±0.05 versus 0.48±0.06 ms/mm Hg) and untreated sham-operated rats (1.21±0.05 versus 0.78±0.17 ms/mm Hg). These results suggest that central endogenous Ang-(1-7) is involved at least in part in the improvement of baroreflex sensitivity observed in 2K1C after peripheral chronic ACE inhibition.
Key Words: angiotensin-(1-7) • baroreflex • 2K1C • hypertension, renal • enalapril • ACE inhibitors
This article has been cited by other articles:
 |
|
 |
|
  A. G. Filho, A. J. Ferreira, S. H. S. Santos, S. R. S. Neves, E. R. Silva Camargos, L. K. Becker, H. A. Belchior, M. F. Dias-Peixoto, S. V. B. Pinheiro, and R. A. S. Santos Selective increase of angiotensin(1-7) and its receptor in hearts of spontaneously hypertensive rats subjected to physical training Exp Physiol, May 1, 2008; 93(5): 589 - 598. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Sakima, D. B. Averill, S. O. Kasper, L. Jackson, D. Ganten, C. M. Ferrario, P. E. Gallagher, and D. I. Diz Baroreceptor reflex regulation in anesthetized transgenic rats with low glia-derived angiotensinogen Am J Physiol Heart Circ Physiol, March 1, 2007; 292(3): H1412 - H1419. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. C. Alzamora, R. A. S. Santos, and M. J. Campagnole-Santos Baroreflex modulation by angiotensins at the rat rostral and caudal ventrolateral medulla Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2006; 290(4): R1027 - R1034. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. A. Tallant, C. M. Ferrario, and P. E. Gallagher Angiotensin-(1-7) inhibits growth of cardiac myocytes through activation of the mas receptor Am J Physiol Heart Circ Physiol, October 1, 2005; 289(4): H1560 - H1566. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Faria-Silva, F. V. Duarte, and R. A.S. Santos Short-Term Angiotensin(1-7) Receptor Mas Stimulation Improves Endothelial Function in Normotensive Rats Hypertension, October 1, 2005; 46(4): 948 - 952. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Sakima, D. B. Averill, P. E. Gallagher, S. O. Kasper, E. N. Tommasi, C. M. Ferrario, and D. I. Diz Impaired Heart Rate Baroreflex in Older Rats: Role of Endogenous Angiotensin-(1-7) at the Nucleus Tractus Solitarii Hypertension, August 1, 2005; 46(2): 333 - 340. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. A.S. Santos, A. S. Haibara, M. J. Campagnole-Santos, A. C. Simoes e Silva, R. D. Paula, S. V.B. Pinheiro, M. de Fatima Leite, V. S. Lemos, D. M.R. Silva, M. T. Guerra, et al. Characterization of a New Selective Antagonist for Angiotensin-(1-7), D-Pro7-Angiotensin-(1-7) Hypertension, March 1, 2003; 41(3): 737 - 743. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Baltatu, M. A. P. Fontes, M. J. Campagnole-Santos, S. Caligiorni, D. Ganten, R. A. S. Santos, and M. Bader Alterations of the renin-angiotensin system at the RVLM of transgenic rats with low brain angiotensinogen Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2001; 280(2): R428 - R433. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. J. Allred, D. I. Diz, C. M. Ferrario, and M. C. Chappell Pathways for angiotensin-(1---7) metabolism in pulmonary and renal tissues Am J Physiol Renal Physiol, November 1, 2000; 279(5): F841 - F850. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. A. P. FONTES, O. BALTATU, S. M. CALIGIORNE, M. J. CAMPAGNOLE-SANTOS, D. GANTEN, M. BADER, and R. A. S. SANTOS Angiotensin peptides acting at rostral ventrolateral medulla contribute to hypertension of TGR(mREN2)27 rats Physiol Genomics, April 27, 2000; 2(3): 137 - 142. [Abstract] [Full Text] [PDF]
|
|