Cardiovascular effects of angiotensin A: A novel peptide of the renin–angiotensin system

• Main Authors: Danielle CO Coutinho, Giselle Foureaux, Keyla DL Rodrigues, Rodrigo LA Salles, Patrícia L Moraes, Tatiane M Murça, Marilda LA De Maria, Enéas RM Gomes, Robson AS Santos, Sílvia Guatimosim, Anderson J Ferreira
• Format: Article
• Language: English
• Published: Hindawi - SAGE Publishing 2014-12-01
• Series: Journal of the Renin-Angiotensin-Aldosterone System
• Online Access: https://doi.org/10.1177/1470320312474856

Introduction: 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 AT 1 R antagonists in certain cardiovascular diseases. Materials and methods: The effects of Ang A and Ang II on blood pressure (BP) and heart function were compared. Importantly, participation of AT 1 R 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. AT 1 R 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.