title: Cardiovascular effects of angiotensin A: a novel peptide of the renin-angiotensin system.
abstract: BACKGROUND
  Angiotensin (Ang) A was first identified in human plasma and it differs from Ang II in Ala(1) instead of Asp(1). Here, we hypothesized that the actions of this peptide might explain, at least partially, the limited effects of AT1R antagonists in certain cardiovascular diseases.
  
  
  METHODS
  The effects of Ang A and Ang II on blood pressure (BP) and heart function were compared. Importantly, participation of AT1R in these effects was evaluated. Furthermore, the effects of these two peptides on ischemia/reperfusion arrhythmias and involvement of calcium in these effects were investigated.
  
  
  RESULTS
  Administration of increasing doses of these peptides caused elevations in BP at comparable magnitude. AT1R blockade completely abolished these effects. The actions of these peptides in cardiac function were quite similar although the effects of Ang A were only partially blocked by losartan. Interestingly, Ang II elicited an increase in the duration of ischemia/reperfusion arrhythmias while Ang A had no effect on cardiac rhythm during reperfusion. In accordance, differently to Ang II, Ang A did not induce any significant effect on calcium transient during baseline and ischemic stress conditions.
  
  
  CONCLUSIONS
  These data suggest that the existence of alternative peptides of the renin-angiotensin system (RAS) might contribute to the limited effects of angiotensin receptor blockers (ARBs) in certain pathophysiological circumstances.
authors: Department of Morphology, Federal University of Minas Gerais, Brazil.
authors: Danielle C O
authors: DC
authors: Coutinho
authors: Department of Morphology, Federal University of Minas Gerais, Brazil.
authors: Giselle
authors: G
authors: Foureaux
authors: Department of Morphology, Federal University of Minas Gerais, Brazil.
authors: Keyla D L
authors: KD
authors: Rodrigues
authors: Department of Morphology, Federal University of Minas Gerais, Brazil.
authors: Rodrigo L A
authors: RL
authors: Salles
authors: Department of Morphology, Federal University of Minas Gerais, Brazil.
authors: Patrícia L
authors: PL
authors: Moraes
authors: Department of Morphology, Federal University of Minas Gerais, Brazil.
authors: Tatiane M
authors: TM
authors: Murça
authors: Department of Morphology, Federal University of Minas Gerais, Brazil.
authors: Marilda L A
authors: ML
authors: De Maria
authors: Department of Physiology and Biophysics, Federal University of Minas Gerais, Brazil.
authors: Enéas R M
authors: ER
authors: Gomes
authors: Department of Physiology and Biophysics, Federal University of Minas Gerais, Brazil.
authors: Robson A S
authors: RA
authors: Santos
authors: Department of Physiology and Biophysics, Federal University of Minas Gerais, Brazil.
authors: Sílvia
authors: S
authors: Guatimosim
authors: Department of Morphology, Federal University of Minas Gerais, Brazil anderson@icb.ufmg.br.
authors: Anderson J
authors: AJ
authors: Ferreira
mesh_terms: D000809:Angiotensins / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D020013:Calcium Signaling / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006334:Heart Function Tests; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000473:pathology / Q000503:physiopathology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology*; D017208:Rats, Wistar; D012084:Renin-Angiotensin System / Q000187:drug effects*
chemical_list: D000809:Angiotensins; D010455:Peptides; C516880:angiotensin A
keywords: AT1 receptor blockers; Angiotensin II; angiotensin-converting enzyme inhibitors; blood pressure; calcium handling; cardiac function