ABSTRACT
RENIN-ANGIOTENSIN SYSTEM The angiotensin-converting enzyme (ACE) regulates the balance between two opposing systems that modulate blood pressure: the renin-angiotensin system (RAS) and the kallikrein-kinin system (Fig. 1). ACE exists in the blood, body fluids, and tissues such as the lung. Increased activity of the RAS leads to salt and water retention and increased vascular tone, which increases blood pressure. Activation of the kallikrein-kinin system leads to the formation of bradykinin, which promotes vasodilatation and natriuresis.
