Cardiovascular Medicine Book

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Renin-Angiotensin SystemAka: Renin, Angiotensin, Angiotensinogen, Angiotensin Converting Enzyme

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  1. Physiology: Overall Process
    1. Step 1: Renin release
      1. Stimulators of renin release
        1. Kidney detects decreased effective blood flow
        2. Increased sympathetic tone
        3. Renal Artery Stenosis
      2. Renin secreted from renal cortex
        1. Secreted from juxtaglomerular cells
        2. Cells located at afferent arteriole of glomerulus
    2. Step 2: Renin mediated step
      1. Renin cleaves angiotensinogen to Angiotensin I
    3. Step 3: Angiotensin-converting enzyme (ACE) mediated
      1. Angiotensin I converted by ACE to Angiotensin II
      2. Conversion by ACE occurs in pulmonary vasculature
    4. Step 4: Angiotensin II Effects
      1. Sodium and water retention
        1. Stimulates aldosterone secretion
        2. Directly affects renal tubule
      2. Vasomotor tone balance
        1. Angiotensin II is a potent vasoconstrictor
          1. Increases systemic vascular resistence
          2. May be Norepinephrine mediated
        2. Antagonist to nitric oxide (potent vasodilator)
  2. Physiology: Angiotensin II Effects
    1. Increases oxygen demand
    2. Increases coronary and renal vasoconstriction
    3. Increases preload and afterload
    4. Predisposes to Left Ventricular Hypertrophy
    5. Increases Catecholamine release (e.g. Norepinephrine)
    6. Increases aldosterone
  3. Agents that decrease Angiotensin II levels
    1. ACE Inhibitors
    2. Angiotensin Receptor Blocker
  4. References
    1. Rose (1987) Pathophysiology of Renal Disease, p. 474-7
    2. Bicket (2002) Am Fam Physician 66(3):461

Angiotensinogen (C0003017)

Definition (MSH)An alpha-globulin of about 453 amino acids, depending on the species. It is produced by the liver and secreted into blood circulation. Angiotensinogen is the inactive precursor of natural angiotensins. Upon successive enzyme cleavages, angiotensinogen yields angiotensin I, II, and III with amino acids numbered at 10, 8, and 7, respectively.
Definition (CSP)a serum alpha-globulin synthesized in the liver, which is cleaved by renin to form angiotensin I.
ConceptsAmino Acid, Peptide, or Protein (T116) , Biologically Active Substance (T123)
EnglishAngiotensinogen, Hypertensinogen, Proangiotensin, Renin Substrate
Spanishangiotensinógeno, angiotensinogeno
CreditsDerived from the NIH UMLS (Unified Medical Language System)


Angiotensins (C0003018)

Definition (MSH)Oligopeptides which are important in the regulation of blood pressure (VASOCONSTRICTION) and fluid homeostasis via the RENIN-ANGIOTENSIN SYSTEM. These include angiotensins derived naturally from precursor ANGIOTENSINOGEN, and those synthesized.
Definition (CSP)angiotensin I, an inactive decapeptide, is cleaved by angiotensin converting enzyme to form the octapeptide angiotensin II, a powerful vasopressor, which is then cleaved to the heptapeptide angiotensin III, an aldosterone stimulant.
Definition (NCI)Expressed in liver by human AGT Gene (Serpin Family), secreted 485-aa 53-kDa Angiotensinogen is cleaved by renin (in response to lowered blood pressure) to inactive decapeptide Angiotensin I, which is cleaved by ACE to generate active octapeptide vasopressor Angiotensin II (maintains blood pressure and regulates the volume and mineral balance of body fluids). Angiotensin II is cleaved to Angiotensin III heptapeptide, an aldosterone stimulant.
ConceptsAmino Acid, Peptide, or Protein (T116) , Pharmacologic Substance (T121) , Biologically Active Substance (T123)
EnglishAngiotensin, Angiotensins
Spanishangiotensina
CreditsDerived from the NIH UMLS (Unified Medical Language System)


Renin (C0035094)

Definition (MSH)A highly specific (Leu-Leu) endopeptidase that generates ANGIOTENSIN I from its precursor ANGIOTENSINOGEN, leading to a cascade of reactions which elevate BLOOD PRESSURE and increase sodium retention by the kidney in the RENIN-ANGIOTENSIN SYSTEM. The enzyme was formerly listed as EC 3.4.99.19.
Definition (CSP)do not confuse with "rennin" which is another name for CHYMOSIN, EC 3.4.23.4.
ConceptsAmino Acid, Peptide, or Protein (T116) , Enzyme (T126)
Englishangiotensin forming enzyme, Angiotensinogenase, Renin
Spanishangiotensinogenasa, enzima formadora de angiotensina, renina
CreditsDerived from the NIH UMLS (Unified Medical Language System)



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