title: Studies directed toward labeling analysis of angiotensin II in plasma.
abstract: We assay a 1-mL plasma sample containing angiotensin II (103 pg by radioimmunoassay) for the hormone by the following sequence of steps: add 125I-labeled val5-angiotensin II as an internal standard, extract on a C18 Sep Pak column, extract on an antibody affinity column, label the extract with an 125I Bolton-Hunter reagent, separate on a Bio Gel P2 column, and repetitively separate on a reversed-phase "high-performance" liquid-chromatographic column, detecting the eluting compounds by counting radioactivity. The fact that we measured 46 pg of angiotensin II-like substance per milliliter in a sample of pooled plasma is encouraging for the further development of this methodology. In particular, replacing the radioisotope with a more suitable chemical label such as an electrophoric (electron-capturing) release tag should be useful.
mesh_terms: D000804:Angiotensin II / Q000097:blood*; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006626:Hippurates / Q000378:metabolism; D006801:Humans; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods*; D011863:Radioimmunoassay; D013388:Succinimides / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D006626:Hippurates; D007457:Iodine Radioisotopes; D013388:Succinimides; D000804:Angiotensin II; C022581:Bolton-Hunter reagent; C046674:hippuryl N-hydroxysuccinimide ester; D014357:Trypsin