Reassessment of plasma angiotensins measurement: effects of protease inhibitors and sample handling procedures. |
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| Authors: | K Kohara Y Tabuchi P Senanayake K B Brosnihan C M Ferrario |
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| Institution: | Department of Brain and Vascular Research, Cleveland Clinic Foundation, OH 44195. |
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| 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. |
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