Secreted angiotensin-converting enzyme (ACE) cleaves 2 amino acid residues from the C-terminus of angiotensin-(1-10) (angiotensin I) to yield angiotensin-(1-8) (angiotensin II) (Wei et al. 1991). This reaction is inhibited by drugs used to treat hypertension (angiotensin converting enzyme inhibitors, ACEI) including captopril (Gronhagen-Riska and Fyhrquist 1980, Stewart et al. 1981, Ehlers et al. 1986, Hayakari et al. 1989, Wei et al. 1991, Baudin and Beneteau-Burnat 1999), enalaprilat (metablized from the prodrug enalapril, Wei et al. 1991, Baudin and Beneteau-Burnat 1999), lisinopril ( Ehlers et al. 1991, Natesh et al. 2003), and ramiprilat (metabolized from the prodrug ramipril, Baudin and Beneteau-Burnat 1999). ACE is secreted ("shed") from membranes of endothelial cells by cleavage in the C-terminal region that removes the membrane anchor.