Abstract
Renin substrate (angiotensinogen) was measured with an assay employing exhaustive incubation of plasma with purified human kidney renin and radioimmunoassay of the angiotensin I (AI) generated. Plasma renin substrate concentration was higher at the age of 3 days (females: 2028 ± 551, males: 1951 ± 565 μg AI/1, mean±SD) than in age group 0–15 years (females: 1513± 555, males: 1263±392μg AI/1). Plasma renin substrate concentration at the age over 15 years (females: 1780±464, males 1752±321 μg AI/1) was higher than in children 0–15 years. Expectedly, high concentrations of plasma renin substrate were found in pregnant women at term (4127 ± 1961 μg AI/1).