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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
A family of peptides of known and similar sequence, with vasoconstrictive activity, produced by enzymatic action of renin on angiotensinogen. See: angiotensin I, angiotensin II, angiotensin III.
Farlex Partner Medical Dictionary © Farlex 2012
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.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
angiotensin(1) Angiotensin I.
(2) Angiotensin II.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
angiotensinAny of a family of vasoconstricting peptides
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
A family of peptides with vasoconstrictive activity, produced by action of renin on angiotensinogen.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
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.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
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.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005