Portal pressure responses and angiotensin peptide production in rat liver are determined by relative activity of ACE and ACE2

Herath, Chandana B. and Lubel, John S. and Jia, Zhiyuan and Velkoska, Elena and Casley, David and Brown, Lindsay and Tikellis, Chris and Burrell, Louise M. and Angus, Peter W. (2009) Portal pressure responses and angiotensin peptide production in rat liver are determined by relative activity of ACE and ACE2. American Journal of Physiology: Gastrointestinal and Liver Physiology, 297 (1). G98-G106. ISSN 0193-1857

Abstract

Angiotensin converting enzyme (ACE) 2 activity and angiotensin-(1-7) [Ang-(1-7)] levels are increased in experimental cirrhosis; however, the pathways of hepatic Ang-(1-7) production have not been studied. This study investigated the role of ACE2, ACE, and neutral endopeptidase (NEP) in the hepatic formation of Ang-(1-7) from angiotensin I (Ang I) and Ang II and their effects on portal resistance. Ang I or Ang II were administered to rat bile duct ligated (BDL) and control livers alone and in combination with the ACE inhibitor lisinopril, the ACE and NEP inhibitor omapatrilat, or the ACE2 inhibitor MLN4760 (n = 5 per group). BDL markedly upregulated ACE, ACE2, and NEP. Ang-(1-7) was produced from Ang II in healthy and in BDL livers and was increased following ACE inhibition and decreased by ACE2 inhibition. In contrast, Ang-(1-7) production from Ang I was minimal and not affected by ACE or NEP inhibition. Surprisingly, ACE2 inhibition in BDLs dramatically increased Ang-(1-7) production from Ang I, an effect abolished by ACE2/NEP inhibition. Ang II and Ang I induced greater portal pressure increases in BDL livers than controls. The effects of Ang I were closely correlated with Ang II production and were strongly attenuated by both ACE and ACE/NEP inhibition. These findings show that the major substrate for hepatic production of Ang-(1-7) is Ang II and this is catalyzed by ACE2. Ang I is largely converted to Ang II by ACE, and net conversion of Ang I to Ang-(1-7) is small. NEP has the ability to generate large amounts of Ang-(1-7) in the BDL liver from Ang I only when ACE2 activity is greatly decreased or inhibited.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Copyright © 2009 the American Physiological Society. Permanent restricted access to paper due to publisher copyright restrictions.
Depositing User: Professor Lindsay Brown
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 17 Dec 2010 11:02
Last Modified: 07 Jul 2014 06:21
Uncontrolled Keywords: hepatic fibrosis; neutral endopeptidase; hepatic resistance; angiotensin peptide metabolism; angiotensin converting enzyme
Fields of Research (FOR2008): 11 Medical and Health Sciences > 1115 Pharmacology and Pharmaceutical Sciences > 111501 Basic Pharmacology
Socio-Economic Objective (SEO2008): C Society > 92 Health > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920199 Clinical Health (Organs, Diseases and Abnormal Conditions) not elsewhere classified
Identification Number or DOI: doi: 10.1152/ajpgi.00045.2009
URI: http://eprints.usq.edu.au/id/eprint/7749

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