The Mas receptor is critically involved in the vascular effects of Ang-(1-7). In fact, many of these actions are completely abolished by A-779 or partially blocked by this antagonist [3, 86, 96] . Importantly, the endothelium-dependent relaxation induced by Ang-(1-7) in mouse aortic rings is absent in vessels derived from Mas-knockout mice [16] . However, other studies have shown that Ang-(1-7) also interacts with ACE, AT 1 , and AT 2 -like receptors, suggesting the existence of additional sites of interaction for Ang-(1-7) [3, 97, 98] . Indeed, Silva et al. [99] reported evidence for the presence of a distinct subtype of Ang-(1-7) receptor sensible to D-pro 7 -Ang-(1-7), a second Mas antagonist, but not to A-779 in aortas of Sprague-Dawley rats.