title: Chymase mediates angiotensin-(1-12) metabolism in normal human hearts.
abstract: Identification of angiotensin-(1-12) [Ang-(1-12)] in forming angiotensin II (Ang II) by a non-renin dependent mechanism has increased knowledge on the paracrine/autocrine mechanisms regulating cardiac expression of Ang peptides. This study now describes in humans the identity of the enzyme accounting for Ang-(1-12) metabolism in the left ventricular (LV) tissue of normal subjects. Reverse phase HPLC characterized the products of (125)I-Ang-(1-12) metabolism in plasma membranes (PMs) from human LV in the absence and presence of inhibitors for chymase (chymostatin), angiotensin-converting enzyme (ACE) 1 (lisinopril) and 2 (MLN-4760), and neprilysin (SHC39370). In the presence of the inhibitor cocktail, ≥ 98% ± 2% of cardiac (125)I-Ang-(1-12) remained intact, whereas exclusion of chymostatin from the inhibitor cocktail led to significant conversion of Ang-(1-12) into Ang II. In addition, chymase-mediated hydrolysis of (125)I-Ang I was higher compared with Ang-(1-12). Negligible Ang-(1-12) hydrolysis occurred by ACE, ACE2, and neprilysin. A high chymase activity was detected for both (125)I-Ang-(1-12) and (125)I-Ang I substrates. Chymase accounts for the conversion of Ang-(1-12) and Ang I to Ang II in normal human LV. These novel findings expand knowledge of the alternate mechanism by which Ang-(1-12) contributes to the production of cardiac angiotensin peptides.
authors: Division of Surgical Sciences, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
authors: Sarfaraz
authors: S
authors: Ahmad
authors: Chih-Chang
authors: CC
authors: Wei
authors: Jose
authors: J
authors: Tallaj
authors: Louis J
authors: LJ
authors: Dell'Italia
authors: Norihito
authors: N
authors: Moniwa
authors: Jasmina
authors: J
authors: Varagic
authors: Carlos M
authors: CM
authors: Ferrario
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000804:Angiotensin II / Q000378:metabolism; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000378:metabolism; D000809:Angiotensins / Q000378:metabolism*; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D053818:Chymases / Q000378:metabolism*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006352:Heart Ventricles / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007093:Imidazoles / Q000378:metabolism; D007150:Immunohistochemistry; D007457:Iodine Radioisotopes; D007930:Leucine / Q000031:analogs & derivatives / Q000378:metabolism; D017706:Lisinopril / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015260:Neprilysin / Q000378:metabolism
chemical_list: C486469:2-(1-carboxy-2-(3-(3,5-dichlorobenzyl)-3H-imidazol-4-yl)ethylamino)-4-methylpentanoic acid; D000806:Angiotensin-Converting Enzyme Inhibitors; D000809:Angiotensins; D007093:Imidazoles; D007457:Iodine Radioisotopes; D000804:Angiotensin II; D017706:Lisinopril; D053818:Chymases; D015260:Neprilysin; D007930:Leucine