Figure 1.

Schematic representation of systemic RAS. The peptides belonging to RAS (AngI, AngII, Ang-(1-5), Ang-(1-7), Ang-(1-9), AngIII, AngIV) are in light blue boxes; renin produced by juxtaglomerular kidney cells and angiotensinogen produced by the liver are in dark blue boxes; the enzymatic actors of RAS are in green boxes: angiotensin converting enzyme (ACE), angiotensin converting enzyme 2 (ACE2), neprilysin (NEP), chymase (CHYM), cathepsin A (CAT${}_{\mathrm{A}}$), thimet oligopeptidase (TO), aminopeptidase A (APA), aminopeptidase N (APN) and prolyloligopeptidase (POP). AngII type 1 receptor (AT1R) is in a red box, with the classical AngII/AT1R axis indicated with a red arrow; the MAS receptor (MASR) is in a deep blue box with the counter-regulatory axis Ang-(1-7)/MASR indicated with a deep blue arrow. The RAS feedback loop is shown with orange arrows. SARS-CoV-2, which acts on ACE2 through the binding of its spike protein, is indicated in magenta.