Mast Cells: The Missing Source of Cardiac Renin?

The renin-angiotensin pathway (RAS). This figure emphasizes only part of the complexity of the RAS. Angiotensin-converting enzyme (ACE) both creates a vasoconstrictor (angiotensin II) and eliminates a vasodilator (bradykinin). Cathepsin D has weak in vitro renin-like activity that may be insignificant under physiologic conditions. Chymase has ACE-like activity, but the in vivo role of chymase is still under debate. AT₁ (Angiotensin II Type 1) and AT₂ are the seven-transmembrane-spanning receptors for the biologically active peptide angiotensin II (1).