Recently, the alternative angiotensin peptide, Ang-(1-9) has shown relevant biological functions. Ocaranza et al. [51] have observed increased ACE2 activity and Ang-(1-9) plasma levels in MI and sham rats treated with enalapril for 8 weeks while circulating Ang-(1-7) levels did not change in any phase after MI [51] (Figure 1 ). These findings support the hypothesis that, in this second arm of the RAS, ACE2 through Ang-(1-9) instead of Ang-(1-7), could act as a counterregulator of the first arm, where ACE catalyzes the formation of Ang II.