Angiotensin I ELISA

Angiotensins are small peptides derived from angiotensinogen. Several of the known angiotensins are established endocrine effectors in the regulation of blood pressure, but they are also known to have other functions locally, in several organs and tis‐ sues (paracrine) and at the cellular level (autocrine / intra‐ crine) 1,2,3,4. Angiotensin I (DRVYIHPFHL) has no known effector function but it is an immediate precursor of Angiotensin II (DRVYIHPF). Angiotensin II binds AT1 receptors, which promote vasoconstriction, sodium retention, release of aldosterone, release of Arg‐vasopressin, cell proliferation, inflammation, fibrosis, anxiety, and cardiac hypertrophy. Angiotensin A (ARVYIHPF)5, and Angiotensin III (RVYIHPF), also bind AT1 re‐ ceptors. Angiotensin (1‐7) (DRVYIHP) binds a different receptor called MAS‐1 which has opposite effects (vasodilation, natriure‐ sis, antiproliferation, NO release, PGE release, and apoptosis)6. Angiotensin IV (VYIHPF) binds yet another receptor called AT4 (IRAP), which promotes increase of blood flow, angiogenesis, and natriuresis, and which has also been implicated in memory formation and in the pathogenesis of Alzheimer’s disease. The peptide LVV‐hemorphin‐7 (LVVYPWTQRF), which is not an an‐ giotensin, also binds the AT4 receptor. There are other angiotensin peptides that have been identified, including Ang (1‐9) (DRVYIHPFH), Ang (1‐12) (DRVYIHPFHLVI), Ang V(3‐7) (VYIHP), as well as several other shorter peptides that have undetermined functions. Angiotensins can be present in very low concentrations in some biological samples. In such cases, dilution of samples to avoid “non‐specific” interference by any present factors is not productive because the angiotensin analyte is also diluted to levels far below the minimum detection concentration. Thus, investigators have used several procedures for extracting angiotensins from biological samples prior to using them for immunoassays. See, for example: a) C18 extraction of Ang I and Ang II from plasma, eluted with ACN:H2O:AcOH (74:24:4)7 ; b) phenylsilylsilica cartridge extraction of Ang (1‐7) from blood, eluted with methanol8. Please see instructions for use for references.