ABSTRACT
INTRODUCTION The renal renin-angiotensin system (RAS) has been established as a modulator of blood pressure and volume homeostasis since the discovery of renin a century ago. In this system angiotensin-converting enzyme (ACE) has been demonstrated to be a unique enzyme because it not only converts angiotensin I (Ang I) to angiotensin II (Ang II) but also inactivates kinins. With the subsequent advent of ACE inhibitors, the importance of the RAS in essential hypertension has been recognized. More recent evidence using molecular and biochemical approaches to angiotensin physiology raises the possibility that there are local RASs distinct from the circulating RAS. Local RAS is thought to act at the tissue or cellular level in paracrine and autocrine systems.
