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Angiotensin I and II in the blood
Last reviewed: 05.07.2025
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The reference concentration (norm) of angiotensin I in blood plasma is less than 25 pg/ml; angiotensin II - 10-60 pg/ml.
Renin, entering the blood from the juxtaglomerular apparatus of the kidneys, cleaves the decapeptide angiotensin I from angiotensinogen, from which, in turn, under the influence of ACE, 2 amino acids are cleaved and angiotensin II is formed. Angiotensin II has two main functions: it stimulates the synthesis and secretion of aldosterone in the adrenal cortex and causes contraction of peripheral blood vessels. Its pressor effect is 30 times higher than that of norepinephrine. In the kidneys, angiotensin II, narrowing the vessels, causes a decrease in blood flow and, as a consequence, a decrease in glomerular filtration. The effect of angiotensin II is short-lived (several minutes), since it is quickly destroyed in the blood under the influence of peptidase (angiotensinase) into inactive fragments.
The study of the concentration of angiotensin I and II in blood plasma is carried out in order to identify the participation of the renin-angiotensin-aldosterone system in the pathogenesis of arterial hypertension, chronic heart failure, and edema syndrome.
Diseases and conditions in which plasma angiotensin activity may change
Angiotensin I is reduced
- Cohn's syndrome (primary hyperaldosteronism)
- Dehydration
- After kidney removal
Angiotensin I is elevated
- Increased blood pressure (renal hypertension)
- Renin-secreting juxtaglomerular tumors
- Kidney cancer with hyperreninemia
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