Abstract P101: Degradation of Ang-(1-7) in Different Mouse Organs

Abstract

Introduction: Ang-(1-7) has cardioprotective effects that serve to counter-regulate adverse effects of Ang II in the cardiovascular system. Angiotensin-(1-7) inhibits pressor, proliferative, and cell growth promoting effects of Ang II. Furthermore, it shows anti-fibrotic and anti-hypertrophic properties in preclinical models of myocardial infarction. It is well accepted that Ang-(1-7) is primarily degraded to Ang-(1-5) by ACE in the cardiovascular system. However, we have preliminary results showing variations exist in Ang-(1-7) degradation pathways in various mouse organs. It is the aim of this study to quantify the metabolites in individual organs and to generate an organ-specific fingerprint of Ang-(1-7) truncation. Methods: Mouse organs were taken from male C57BL/6J mice and homogenates/membranes were prepared and measured for protein concentration. Membrane isolations were incubated with Ang-(1-7) and analyzed for peptide identification on an LCMS system. Results: Our results show that after 10 minutes Ang-(1-7) is degraded fastest in lung (1% [88108/6837249] of peptide remaining), followed by Kidney (8% [544423/6837249]), then liver (41% [2781701/6837249]), ventricle (83% [5699496/6837249]), and brain (86% [5868630/6837249]). Unsurprisingly, Ang-(1-5) was a major degradation product for the lung, kidney, and heart. However, we identified Ang-(1-4) as another major degradation product in lung and kidney. In contrast, the major degradation product of Ang-(1-7) in the brain and ventricle was Ang-(2-7). While Ang-(1-7) metabolism in testes yielded a unique angiotensin metabolite not observed in other tissues, Ang-(1-7) was not at all converted in atrium membranes. Conclusions: Ang-(1-7) degradation varies greatly in speed and metabolites between mouse organs. The necessity to update the relatively old canonical Ang-(1-7) degradation pathway is paramount for drug viability and design. By identifying the peptidases ultimately responsible for the metabolism of Ang-(1-7), its circulating concentration can be increased, thus improving the benefits of its cardiovascular protective effects.