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World J Ophthalmol. Aug 12, 2015; 5(3): 110-124
Published online Aug 12, 2015. doi: 10.5318/wjo.v5.i3.110
Ocular renin-angiotensin system with special reference in the anterior part of the eye
Mervi Holappa, Heikki Vapaatalo, Anu Vaajanen
Mervi Holappa, BioMediTech, University of Tampere, 33520 Tampere, Finland
Heikki Vapaatalo, Institute of Biomedicine, Pharmacology, University of Helsinki, 00014 Helsinki, Finland
Anu Vaajanen, Department of Ophthalmology, Tampere University Hospital, 33521 Tampere, Finland
Anu Vaajanen, SILK, Department of Ophthalmology, School of Medicine, University of Tampere, 33521 Tampere, Finland
Author contributions: Holappa M collected the literature, prepared the tables and wrote the preliminary version; Vapaatalo H revised the text; and Vaajanen A revised the text and submitted the article.
Supported by Päivikki and Sakari Sohlberg Foundation; the Eye Foundation; the Glaucoma Research Foundation Lux; the Competitive Research Funding of Tampere University Hospital, No. 9S072; and the Foundation for Clinical Chemistry Research.
Conflict-of-interest statement: No competing interests.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Anu Vaajanen, MD, PhD, Department of Ophthalmology, Tampere University Hospital, P.O. Box 2000, 33521 Tampere, Finland. anu.vaajanen@fimnet.fi
Telephone: +358-3-31164852 Fax: +358-3-31164365
Received: January 28, 2015
Peer-review started: January 29, 2015
First decision: March 6, 2015
Revised: June 4, 2015
Accepted: June 15, 2015
Article in press: June 16, 2015
Published online: August 12, 2015
Processing time: 200 Days and 20.4 Hours
Abstract

The renin-angiotensin system (RAS) regulates blood pressure (BP) homeostasis, systemic fluid volume and electrolyte balance. The RAS cascade includes over twenty peptidases, close to twenty angiotensin peptides and at least six receptors. Out of these, angiotensin II, angiotensin converting enzyme 1 and angiotensin II type 1 receptor (AngII-ACE1-AT1R) together with angiotensin (1-7), angiotensin converting enzyme 2 and Mas receptor (Ang(1-7)-ACE2-MasR) are regarded as the main components of RAS. In addition to circulating RAS, local RA-system exists in various organs. Local RA-systems are regarded as tissue-specific regulatory systems accounting for local effects and long term changes in different organs. Many of the central components such as the two main axes of RAS: AngII-ACE1-AT1R and Ang(1-7)-ACE2-MasR, have been identified in the human eye. Furthermore, it has been shown that systemic antihypertensive RAS- inhibiting medications lower intraocular pressure (IOP). These findings suggest the crucial role of RAS not only in the regulation of BP but also in the regulation of IOP, and RAS potentially plays a role in the development of glaucoma and antiglaucomatous drugs.

Keywords: Angiotensin converting enzyme 1; Angiotensin converting enzyme 2; Angiotensin converting enzyme-inhibitors; Angiotensin II; Angiotensin (1-9); Angiotensin (1-7); Glaucoma; Intraocular pressure; Renin-angiotensin system

Core tip: Many of the central components of renin-angiotensin system (RAS) have been identified in different structures of the human eye. Recent findings suggest that local RAS accounts for long term changes in ocular tissue level. Antihypertensive drugs which inhibit RAS (Angiotensin converting enzyme or AT-receptor blockade) reduce intraocular pressure suggesting their possibility as anti-glaucomatous drugs in the future. Here we describe the local intraocular RAS especially in the anterior part of eye.