angiotensin

(ACE) [an″je-o-ten´sin]

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.

ACE2

(1) Angiotensin-Converting Enzyme 2. An angiotensin-converting enzyme (ACE-like exopeptidase of the dipeptidyl carboxydipeptidase family) which is expressed predominantly in vascular endothelial cells of the heart, kidney and testes.
Physiology ACE2 appears to be a critical regulator of heart function and may counteract ACE activity.
(2) A gene on Xp22 which encodes a variant of angiotensin converting enzyme of the dipeptidyl carboxydipeptidase family, which is expressed on the vascular endothelial cells of the heart, kidneys and testes.