The Renin-Angiotensin System: Emerging Concepts

The renin-angiotensin system (RAS) is a pivotal regulator of the renal and cardiovascular functions playing an important role in the control of blood pressure and hydroelectrolyte balance. In the past few years the combination of classical physiopharmacological techniques with modern genomics and protein chemistry methods has lead to the identification of important novel components of the RAS: the Angiotensin (Ang) IV binding site IRAP (insulin-regulated aminopeptidase), the angiotensin-converting enzyme 2 (ACE2), and the Ang-(1-7) receptor Mas. Ang-(1-7) is one of the most interesting peptide fragments of the RAS because it has actions which are often opposite to those of Ang II. The recent identification of the Ang-(1-7) forming enzyme ACE2 and of Mas as an Ang-(1-7) receptor has added further support and more widely acceptance to a new concept of the RAS in which the system has two major arms: a vasoconstrictor/proliferative in which the major player is Ang II and a vasodilator/anti-proliferative in which the major effector is Ang-(1-7). In this article we will briefly review these novel aspects related to the RAS with focus on the possible physiological role of the ACE2-Ang-(1-7)-Mas axis in the cardiovascular system.