Review Article

Renin Angiotensin System in Cognitive Function and Dementia

Figure 4

A schematic representation of the renin-angiotensin system. Additional components of the renin-angiotensin system (RAS) pathway have been identified in recent years, increasing its complexity. Angiotensin metabolites are prefixed by Ang, with the number of amino acids present relative to the 14 amino acid angiotensinogen sequence order. Arrows between peptide fragments denote enzymatic conversion steps catalyzed by a host of enzymes denoted by coloured circles or boxes according to the abbreviations listed below. Arrows from peptides to boxes denote receptor binding routes. Note that the Ang II metabolite Ang III is currently considered to be the main and a more potent mediator of many recognized Ang II functions, and the binding of Ang IV to its receptor is believed to affect cognitive function. Also note the ACE2-Ang(1–7)-Mas (receptor) axis, which is now currently believed to be a RAS internal regulatory mechanism to attenuate Ang II-mediated functions (large red arrow centrally located in pathway; ACE2 is a recently discovered ACE homologue). ACE: angiotensin-1 converting enzyme; AP: aminopeptidase; DAP: dipeptidyl aminopeptidase; PCP: carboxypeptidase; PO: propyl oligopeptidase; REN: renin.
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