Recent insights and therapeutic perspectives of angiotensin-(1–9) in the cardiovascular system

Chronic RAS (renin–angiotensin system) activation by both AngII (angiotensin II) and aldosterone leads to hypertension and perpetuates a cascade of pro-hypertrophic, pro-inflammatory, pro-thrombotic and atherogenic effects associated with cardiovascular damage. In 2000, a new pathway consisting of ACE2 (angiotensin-converting enzyme2), Ang-(1–9) [angiotensin-(1–9)], Ang-(1–7) [angiotensin-(1–7)] and the Mas receptor was discovered. Activation of this novel pathway stimulates vasodilation, anti-hypertrophy and anti-hyperplasia. For some time, studies have focused mainly on ACE2, Ang-(1–7) and the Mas receptor, and their biological properties that counterbalance the ACE/AngII/AT₁R (angiotensin type 1 receptor) axis. No previous information about Ang-(1–9) suggested that this peptide had biological properties. However, recent data suggest that Ang-(1–9) protects the heart and blood vessels (and possibly the kidney) from adverse cardiovascular remodelling in patients with hypertension and/or heart failure. These beneficial effects are not modified by the Mas receptor antagonist A779 [an Ang-(1–7) receptor blocker], but they are abolished by the AT₂R (angiotensin type 2 receptor) antagonist PD123319. Current information suggests that the beneficial effects of Ang-(1–9) are mediated via the AT₂R. In the present review, we summarize the biological effects of the novel vasoactive peptide Ang-(1–9), providing new evidence of its cardiovascular-protective activity. We also discuss the potential mechanism by which this peptide prevents and ameliorates the cardiovascular damage induced by RAS activation.