Angiotensin III

Angiotensin III is a peptide hormone that is part of the RAS, a hormone system that regulates blood pressure and fluid balance. It is a derivative of Angiotensin II, and has a significant role in maintaining blood pressure and volume homeostasis.

Structure

Angiotensin III is a hexapeptide, meaning it is composed of six amino acids. It is derived from angiotensin II by the removal of one amino acid, a process catalyzed by the enzyme Aminopeptidase A. The resulting structure is less complex than that of angiotensin II, but it retains the ability to bind to and activate the same receptors.

Function

Angiotensin III has several functions in the body, many of which are similar to those of angiotensin II. It can bind to and activate the AT1 receptor and the AT2 receptor, both of which are involved in regulating blood pressure. Activation of these receptors leads to vasoconstriction, or narrowing of the blood vessels, which increases blood pressure.

In addition to its role in blood pressure regulation, angiotensin III also stimulates the release of aldosterone, a hormone that increases sodium reabsorption in the kidneys. This leads to an increase in blood volume and, consequently, an increase in blood pressure.

Clinical Significance

Due to its role in blood pressure regulation, angiotensin III is a potential target for the treatment of hypertension. Drugs that inhibit the production of angiotensin III, such as ACE inhibitors, are commonly used to treat high blood pressure. Additionally, drugs that block the receptors that angiotensin III binds to, known as ARBs, are also used in hypertension treatment.

See Also

• Angiotensin
• Renin-Angiotensin System
• Hypertension