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Chymase‐dependent generation of Angiotensin II from Angiotensin‐(1–12) in human atrial tissue
Author(s) -
Ahmad Sarfaraz,
Varagic Jasmina,
Westwood Brian,
Chappell Mark C.,
Strawn William B.,
Simmons Tony,
Ferrario Carlos M.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.605.4
Subject(s) - chymase , neprilysin , chemistry , renin–angiotensin system , angiotensin ii , medicine , endocrinology , angiotensin converting enzyme , enzyme , angiotensin iii , atrial natriuretic peptide , angiotensin converting enzyme 2 , peptide , receptor , angiotensin ii receptor type 1 , biochemistry , biology , blood pressure , disease , covid-19 , infectious disease (medical specialty)
We showed that angiotensin‐(1–12) [Ang‐(1–12)] is a non‐renin dependent alternate precursor for the generation of cardiac Ang peptides in rat tissue. In this study, we investigated the metabolism of Ang‐(1–12) by plasma membranes (PM) isolated from human atrial appendage tissue from patients undergoing open‐heart surgery. PM were incubated with highly purified 125 I‐Ang‐(1–12) at 37° C for 1 h with or without a cocktail of peptidase inhibitors for ACE, ACE2, neprilysin (NEP) and chymase (50 μM each). 125 I‐peptide fractions were identified in the supernatant by HPLC coupled to an inline γ‐detector. In the absence of inhibitor, 125 I‐Ang‐(1–12) was converted into Ang I (10±7%), Ang II (62±14%), Ang‐(1–7) (7±3%) and other smaller peptides (<2%). In the presence of the all inhibitors, 90±4% of 125 I‐Ang‐(1–12) remained intact. The relative contribution of selective inhibition of ACE, ACE2, NEP, and chymase enzyme showed that 125 I‐Ang‐(1–12) was primarily converted into Ang II (77±24%) by chymase while its hydrolysis into Ang peptides by ACE, ACE2 and NEP was significantly lower. The activity of individual enzyme was then calculated based on the formation of Ang I, Ang II, Ang‐(1–7) peptides fractions. These results showed a very high chymase activity (54±22 fmol × min −1 × mg protein −1 , N=5), followed by ACE2, and NEP (10.5±6 and 7.3±5.6 fmol × min −1 × mg protein −1 , respectively) while ACE activity was negligible (2.8±2.1 fmol × min −1 × mg protein −1 ). In conclusion, we demonstrate for the first time in human cardiac tissue a dominant role of cardiac chymase in the formation of angiotensins peptides from Ang‐(1–12).