An alternative strategy for the radioimmunoassay of angiotensin peptides using amino-terminal-directed antisera: measurement of eight angiotensin peptides in human plasma

We describe here a method of measuring angiotensin peptides and their carboxy-truncated metabolites in human plasma using N-terminal-directed antisera. Antisera raised against N-acetylated angiotensin (Ang) II and N-acetylated Ang III analogues were used to develop two radioimmunoassays. Extracted plasma samples were acetylated prior to separation of cross-reacting angiotensin peptides by high-performance liquid chromatography (HPLC). Fractions were assayed with both antisera to obtain measurements for eight angiotensin peptides. Angiotensin levels measured in normal males were (fmol/ml plasma, means ± s.e.m., n=14)Ang-(1—7) 1.0 ± 0.2, Ang II 13.9 ±2.0, Ang-(1-9) 7lt;0.4, Ang I 19.5 ± 2.4, Ang-(2-7)