ACE inhibitor refers to any agent that inhibits the Angiotensin Converting Enzyme (ACE) that converts angiotensin I to angiotensin II. ACE is created and secreted by cells in the lungs and kidneys to help regulate blood pressure and maintain homeostasis in the body.
Angiotensin II is a substance in the body that acts to constrict blood vessels and increase blood pressure (it is a vasoconstrictor). By preventing the conversion of angiotensin I to angiotensin II, ACE inhibitors prevent this blood vessel constriction. Angiotensin II also promotes the release of a hormone called aldosterone into your body. Aldosterone works on your kidneys to promote water and salt retention which will naturally increase your blood volume and blood pressure.
In addition to working on the angiotensin I to II conversion, ACE enzymes work in the breakdown of a substance called bradykinin. Bradykinin is a substance that acts to open up blood vessels (it is a vasodilator). ACE inhibitors prevent the breakdown of bradykinin in the body, thereby encouraging the blood vessels to open up.
By preventing the production of angiotensin II and the breakdown of bradykinin, ACE inhibitors can reduce a persons' blood pressure, making ACE inhibitors useful for the prevention and treatment of heart disease.
There are many different ACE inhibitors available on the market, including (but not limited to): ramipril, perindopril, enalapril, captopril, lisinopril and fosinopril.