title: Reassessment of plasma angiotensins measurement: effects of protease inhibitors and sample handling procedures.
abstract: Characterization of C- and N-terminal forms of angiotensin (Ang) peptides mandated assessment of methods to determine plasma levels. 125I-Ang I, 125I-Ang II, and 125I-Ang(1-7) were added to blood samples in the presence of protease inhibitors. Ethylenediaminetetraacetic acid (EDTA) inhibited the conversion of 125I-Ang I to 125I-Ang II. o-Phenanthroline and EDTA (EDTA + o-Ph) did not eliminate [des-Asp1] fragments or 125I-Ang(1-7). The combination of EDTA + o-Ph and pepstatin A or 4-(chloromercuri) benzoic acid (PCMB) significantly reduced 125I-Ang(1-7) generation. Only PCMB plus EDTA + o-Ph eliminated [des-Asp1] fragments. Authentic plasma values of Ang peptides require the correct choice of protease inhibitors.
authors.affiliation: Department of Brain and Vascular Research, Cleveland Clinic Foundation, OH 44195.
authors.forename: K
authors.initials: K
authors.lastname: Kohara
authors.forename: Y
authors.initials: Y
authors.lastname: Tabuchi
authors.forename: P
authors.initials: P
authors.lastname: Senanayake
authors.forename: K B
authors.initials: KB
authors.lastname: Brosnihan
authors.forename: C M
authors.initials: CM
authors.lastname: Ferrario
mesh_terms: D000803:Angiotensin I / Q000032:analysis / Q000097:blood*; D000804:Angiotensin II / Q000032:analysis / Q000097:blood*; D000818:Animals; D001800:Blood Specimen Collection / Q000379:methods; D002729:Chloromercuribenzoates / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D004492:Edetic Acid / Q000494:pharmacology; D015773:Enalaprilat / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology*; D020245:p-Chloromercuribenzoic Acid
chemical_list: D002729:Chloromercuribenzoates; D011480:Protease Inhibitors; D000804:Angiotensin II; D020245:p-Chloromercuribenzoic Acid; D000803:Angiotensin I; D004492:Edetic Acid; D015773:Enalaprilat