angiotensin(redirected from ATII)
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a vasoconstrictive substance formed in the blood when renin is released from the juxtaglomerular apparatus in the kidney. The enzymatic action of renin acts on angiotensinogen to form the decapeptide angiotensin I, which is relatively inactive. It in turn is acted upon by peptidases (converting enzymes), chiefly in the lungs, to form the octapeptide angiotensin II, a powerful vasopressor and a stimulator of aldosterone secretion by the adrenal cortex. By its vasopressor action, it raises blood pressure and diminishes fluid loss in the kidney by restricting blood flow. Angiotensin II is hydrolyzed in various tissues to form heptapeptide angiotensin III, which has less vasopressor activity but more effect on the adrenal cortex.
angiotensin-converting enzyme (ACE) an enzyme of the hydrolase class that catalyzes cleavage of a dipeptide from the C-terminal end of angiotensin I to form activated angiotensin II; called also peptidyl-dipeptidase A.
angiotensin-converting enzyme inhibitors competitive inhibitors of angiotensin-converting enzyme, which converts angiotensin I to angiotensin II and inactivates bradykinin. ACE inhibitors, such as captopril, are antagonists of the renin-angiotensin-aldosterone system and potentiators of the kinin system and are used for treatment of hypertension, usually in conjunction with a diuretic. They are also used as vasodilators in the treatment of congestive heart failure.
angiotensin/an·gio·ten·sin/ (-ten´sin) a decapeptide hormone (a. I) formed from the plasma glycoprotein angiotensinogen by renin secreted by the juxtaglomerular apparatus. It is in turn hydrolyzed by a peptidase in the lungs to form an octapeptide (a. II), which is a powerful vasopressor and stimulator of aldosterone secretion by the adrenal cortex. This is in turn hydrolyzed to form a heptapeptide (a. III), which has less vasopressor activity but more adrenal cortex–stimulating activity.
Any of several polypeptide hormones, designated by Roman numerals, that are involved in the regulation of blood pressure, especially one of them, angiotensin II, which is a strong vasopressor.
Etymology: Gk, angeion + L, tendere, to stretch
a polypeptide in the blood that causes vasoconstriction, increased blood pressure, and the release of aldosterone from the adrenal cortex. Angiotensin is formed by the action of renin on angiotensinogen, an alpha-2-glycoprotein that is produced in the liver and that constantly circulates in the blood. Renin, stimulated by juxtaglomerular cells in the kidney in response to decreased blood volume and serum sodium levels, acts as an enzyme in the conversion of angiotensinogen to angiotensin I, which is rapidly hydrolyzed to form the active compound, angiotensin II. The vasoconstrictive action of angiotensin II decreases the glomerular filtration rate, and the concomitant action of aldosterone promotes sodium retention, with the result that blood volume and sodium reabsorption increase. Plasma angiotensin II increases during the luteal phase of the menstrual cycle and is probably responsible for an elevated level of aldosterone during that period. Angiotensin is inactivated by peptidases, called angiotensinases, in plasma and tissues.
angiotensin(1) Angiotensin I.
(2) Angiotensin II.
angiotensinAny of a family of vasoconstricting peptides
A family of peptides with vasoconstrictive activity, produced by action of renin on angiotensinogen.
angiotensinThe vasoconstrictor polypeptide hormone, angiotensin II, which is released by the action of the enzyme renin. Its precursor, angiotensin I, is inactive until acted on by the angiotensin-converting enzyme, mainly in the lungs. Angiotensin II has a powerful effect on raising the blood pressure. It binds to angiotensin receptors and constricts the circular smooth muscle of blood vessel walls. It prompts cells of the adrenal cortex to secrete the hormone ALDOSTERONE. It modulates blood flow through the kidneys and acts directly on the heart muscle. By promoting raised blood pressure it encourages the development of the arterial disease ATHEROSCLEROSIS.
angiotensina substance, produced by the action of RENIN on a GLOBULIN protein molecule, that is found in blood plasma and which then stimulates the cortex of the ADRENAL GLAND to release ALDOSTERONE, causing a general constriction of smooth muscle.
angiotensinsubstance derived from angiotensinogen in the blood, by the action of the enzyme renin secreted by the kidneys. angiotensin-converting enzyme (ACE): an enzyme, principally in kidney and lung endothelia, which catalyses conversion of the inactive form angiotensin I in the blood to angiotensin II; this in turn stimulates release of aldosterone from the adrenal glands and hence sodium reabsorption in kidneys. This renin-angiotensin-aldosterone system is important in the normal regulation of blood volume and arterial blood pressure. There are recent indications that either ACE itself, or perhaps some other molecule(s) whose biosynthesis is enhanced in parallel by the ACE gene, favour(s) various aspects of physical performance.
angiotensinvasoactive peptides that promote vasoconstriction, whose action is suppressed by angiotensin-converting enzyme inhibitors
a vasoconstrictive principle formed in the blood when renin is released from the juxtaglomerular apparatus in the kidney. The enzymatic action of renin cleaves a serum α2-globulin, angiotensinogen, forming the decapeptide angiotensin I, which is relatively inactive. It in turn is acted upon by peptidases (converting enzymes), chiefly in the lungs, to form the octapeptide angiotensin II, a powerful vasopressor and a stimulator of aldosterone secretion by the adrenal cortex. By its vasopressor action, it raises blood pressure and diminishes fluid loss in the kidney by restricting blood flow. Angiotensin II is hydrolyzed in various tissues to form heptapeptide angiotensin III, which has less vasopressor activity but more effect on the adrenal cortex.
an amide derivative of angiotensin II which is a powerful vasoconstrictor and vasopressor, and is used in the treatment of certain hypotensive states; usually administered by slow intravenous infusion, and sometimes intramuscularly or subcutaneously.
angiotensin-converting enzyme (ACE)
a peptidase which catalyzes the formation of angiotensin II from angiotensin I. See also ace.