renin /re·nin/ (re´nin) a proteolytic enzyme synthesized, stored, and secreted by the juxtaglomerular cells of the kidney; it plays a role in regulation of blood pressure by catalyzing the conversion of angiotensinogen to angiotensin I.
Renin
renin
renin [re´nin]
re·nin (r  n n, r nn)n. A protein-digesting enzyme that is released by the kidneys and that catalyzes the hydrolysis of angiotensinogen to angiotensin I. Also called angiotensinogenase. |
Renin
An enzyme produced in the kidneys that controls the activation of the hormone angiotensin, which stimulates the adrenal glands to produce aldosterone.
Mentioned in: Aldosterone Assay
renin
[rē′nin]
Etymology: L, ren, kidney
a renal proteolytic enzyme, produced by and stored in the juxtaglomerular apparatus that surrounds each arteriole as it enters a glomerulus. The enzyme affects the blood pressure by catalyzing the change of angiotensinogen to angiotensin I, which is then converted to angiotensin II, strong pressor. Normal findings of adult plasma renin, measured in an upright position and sodium depleted, are 2.9 to 10.8 ng/mL/hr. Compare rennin.
renin [re´nin]
a proteolytic enzyme synthesized, stored, and secreted by the juxtaglomerular cells of the kidney; it plays a role in regulation of blood pressure by catalyzing the conversion of the plasma glycoprotein angiotensinogen to angiotensin I. This, in turn, is converted to angiotensin II by an enzyme that is present in relatively high concentrations in the lung. Angiotensin II is one of the most potent vasoconstrictors known, and also is a powerful stimulus of aldosterone secretion.
Stimuli to the secretion of renin include sodium depletion, dehydration, serum albumin depletion, cirrhosis of the liver, cardiac failure, renal artery stenosis, and renal nerve stimulation.
Whenever blood flow to the kidney diminishes, renin is secreted and angiotensin is formed. The angiotensin causes widespread vasoconstriction and elevation of blood pressure consequent to greatly increased total peripheral resistance. A second effect, the increased secretion of aldosterone, results in retention of salt and water by the kidneys and therefore increased extracellular fluid volume, cardiac output, and arterial pressure. Additionally, the angiotensin acts directly on the kidneys to cause salt and water retention, which causes a long-term increase in arterial blood pressure.
Stimuli to the secretion of renin include sodium depletion, dehydration, serum albumin depletion, cirrhosis of the liver, cardiac failure, renal artery stenosis, and renal nerve stimulation.
Whenever blood flow to the kidney diminishes, renin is secreted and angiotensin is formed. The angiotensin causes widespread vasoconstriction and elevation of blood pressure consequent to greatly increased total peripheral resistance. A second effect, the increased secretion of aldosterone, results in retention of salt and water by the kidneys and therefore increased extracellular fluid volume, cardiac output, and arterial pressure. Additionally, the angiotensin acts directly on the kidneys to cause salt and water retention, which causes a long-term increase in arterial blood pressure.
renin-angiotensin-aldosterone system the regulation of sodium balance, fluid volume, and blood pressure by secretion of renin in response to reduced perfusion of the kidney. Renin hydrolyzes a plasma globulin to release angiotensin I, which is rapidly hydrolyzed to angiotensin II, which in turn stimulates aldosterone secretion. Aldosterone brings about sodium retention, water retention, increase in blood pressure, and restoration of renal perfusion, which shuts off the signal for renin release. Angiotensin II is a potent vasoconstrictor, which also increases blood pressure.
The role of the renin-angiotensin-aldosterone system in regulation of blood pressure. Solid lines represent positive interactions; broken lines show negative interactions or feedback inhibition. From Cotran et al., 1994.
big renin prorenin.
renin
a proteolytic enzyme synthesized, stored and secreted by the juxtaglomerular cells of the kidney; it plays a role in regulation of blood pressure by catalyzing the conversion of the plasma glycoprotein angiotensinogen to angiotensin I. This, in turn, is converted to angiotensin II by an enzyme that is present in relatively high concentrations in the lung. Angiotensin II is one of the most potent vasoconstrictors known, and also is a powerful stimulus of aldosterone secretion.
renin-angiotensin system
renin, secreted by the juxtaglomerular apparatus, activates the precursor angiotensinogen. This liberates angiotensin I, then angiotensin II, a vasoconstrictor and stimulant to the secretion of aldosterone.
big renin
a relatively inactive protein with a higher molecular weight than normal renin, which is activated after exposure to low pH or to proteolytic enzymes.
renin
Physiology An aspartyl proteinase with one substrate, angiotensinogen, which is secreted primarily by the granular cells of the juxtaglomerular apparatus, as well as the brain and endothelial cells, in response to ↓ renal perfusion
pressure or ↓ kallikrein; renin cleaves angiotensinogen to yield angiotensin I–a decapeptide, the precursor of angiotensin II–an octapeptide, and angiotensin III–a heptapeptide; the latter 2 are potent vasoconstrictors, and
stimulate thirst and ↑ aldosterone production ↑ in Addison's disease, COPD, CRF hypersecretion, eclampsia–and preeclampsia, hyperthyroidism, cirrhosis, ↓ K+, ↓ salt diet, malignant HTN, pregnancy, renal failure,
renovascular HTN, functional kidney tumors, drugs–eg, antihypertensives, diuretics, estrogens, OCs ↓ in Cushing syndrome, DM, essential HTN, hypothyroidism, high salt diet, drugs–eg, antihypertensives, levodopa, propranol. Cf
Hypertension, Plasma renin activity.
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