A Simple Method for Measurement of Angiotensin II in Plasma

Abstract

Kosunen, K. J. A Simple Method for Measurement of Angiotensin II in Plasma. Scand. J. clin. Lab. Invest. 36, 467–472, 1976.

A simple radioirrtmunological (RIA) method for the determination of angiotensin II in 0.5–1.0 ml samples of plasma is described and carefully evaluated. Before RIA was performed, the interfering plasma proteins were eliminated by ion exchange chromatography, and recovery from every column was checked with a small amount of [¹²⁵I]angiotensin II. The sensitivity of the method was 4.0 ng/1; the coefficient of intra-assay variation was 10.0% and that of inter-assay variation 12.1%. Accuracy was studied both by adding various amounts of angiotensin II to plasma samples and by diluting plasma containing angiotensin II with the RIA buffer. Both studies gave very good correlations between found and expected values (r=0.998 and r=0.987). In a normal material (n=36), the mean angiotensin II concentration at 8 a.m. after a night's bed rest was 31.1 ±10.7 (S.D.) ng/1 and at 10 a.m. after 2 h ambulation 42.4±12.8 (S.D.) ng/1. Because the present method is accurate, precise, and practical, and allows measurement of angiotensin II in small samples, it seems useful for routine as well as for research work.

Key Words:

• Angiotensin II
• radioimmunoassay