renin

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.

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re·nin (rnn, rnn)

n.

A protein-digesting enzyme that is released by the kidneys and that catalyzes the hydrolysis of angiotensinogen to angiotensin I. Also called angiotensinogenase.

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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

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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.

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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.

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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.

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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.