Faculty Collaboration Database

Angiotensin I is largely converted to angiotensin (1-7) and angiotensin (2-10) by isolated rat glomeruli. Hypertension 2009 May;53(5):790-7

Date

03/18/2009

Pubmed ID

19289651

Pubmed Central ID

PMC2706530

DOI

10.1161/HYPERTENSIONAHA.109.128819

Scopus ID

2-s2.0-73549113815 (requires institutional sign-in at Scopus site)   50 Citations

Abstract

Intraglomerular renin-angiotensin system enzyme activities have been examined previously using glomerular lysates and immune-based assays. However, preparation of glomerular extracts compromises the integrity of their anatomic architecture. In addition, antibody-based assays focus on angiotensin (Ang) II detection, ignoring the generation of other Ang I-derived metabolites, some of which may cross-react with Ang II. Therefore, our aim was to examine the metabolism of Ang I in freshly isolated intact glomeruli using matrix-assisted laser desorption ionization time of flight mass spectrometry as an analytic method. Glomeruli from male Sprague-Dawley rats were isolated by sieving and incubated in Krebs buffer in the presence of 1 micromol/L of Ang I for 15 to 90 minutes, with or without various peptidase inhibitors. Peptide sequences were confirmed by matrix-assisted laser desorption ionization time of flight tandem mass spectrometry or linear-trap-quadrupole mass spectrometry. Peaks were quantified using customized valine-(13)C(.15)N-labeled peptides as standards. The most prominent peaks resulting from Ang I cleavage were 899 and 1181 m/z, corresponding with Ang (1-7) and Ang (2-10), respectively. Smaller peaks for Ang II, Ang (1-9), and Ang (3-10) also were detected. The disappearance of Ang I was significantly reduced during inhibition of aminopeptidase A or neprilysin. In contrast, captopril did not alter Ang I degradation. Furthermore, during simultaneous inhibition of aminopeptidase A and neprilysin, the disappearance of Ang I was markedly attenuated compared with all of the other conditions. These results suggest that there is prominent intraglomerular conversion of Ang I to Ang (2-10) and Ang (1-7), mediated by aminopeptidase A and neprilysin, respectively. Formation of these alternative Ang peptides may be critical to counterbalance the local actions of Ang II. Enhancement of these enzymatic activities may constitute potential therapeutic targets for Ang II-mediated glomerular diseases.

Author List

Velez JC, Ryan KJ, Harbeson CE, Bland AM, Budisavljevic MN, Arthur JM, Fitzgibbon WR, Raymond JR, Janech MG

Author

John R. Raymond MD President, CEO, Professor in the President department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Angiotensin I
Animals
Glutamyl Aminopeptidase
Kidney Glomerulus
Male
Neprilysin
Peptide Fragments
Rats
Rats, Sprague-Dawley
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization