Angiotensin I radioimmunoassay

Antiserum to angiotensin I was prepared by rabbit immunization with a conjugate of angiotensin I with hemocyanin. The radioimmunoassay of angiotensin I was used for the determination of plasma renin activity. Chelaton 3 and 2,3-dimercapto-1-propanol were used for inhibition of the enzyme transforming angiotensin I to angiotensin II and of angiotensinases. The radioimmunoassay of angiotensins is carried out at 4 degC to suppress renin activity. The values of intra- and inter-variation coefficients were 6.5-8.3% and 7.1-12.3%, respectively. The yields of angiotensin I added to the plasma were from 94.6 to 106.9%. The determination sensitivity of 5 pg angiotensin I per test tube (which corresponds to a plasma renin activity of 0.133 ng/ml.h) and the good correlation with the established commercial radioimmunoassay of angiotensin I (r=0.998) make this method suitable for routine use. (author)