Figure 1.

Schematic diagram showing the role of angiotensin-converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) in the degradation of bradykinin and substance P. Studies in rodents suggest that DPP-IV is the primary enzyme responsible for the inactivation of substance P when ACE is inhibited.²⁶ The dotted line indicates that bradykinin is already inactivated by aminopeptidase P (APP) before it is degraded further by DPP-IV. CPN indicates carboxypeptidase N; NEP indicates neutral endopeptidase.