Angiotensin I

Angiotensin I is a peptide hormone that plays a crucial role in the renin-angiotensin system, a complex system that regulates blood pressure and fluid balance in the body. It is produced by the action of renin, an enzyme released by the kidneys, on angiotensinogen, a protein produced by the liver and released into the bloodstream.

Production and Function

Angiotensin I is a decapeptide, meaning it is composed of ten amino acids. It is produced when renin, which is released by the kidneys in response to low blood pressure or low sodium levels, acts on angiotensinogen. This reaction takes place in the bloodstream and results in the conversion of angiotensinogen into angiotensin I.

Although angiotensin I has little biological activity on its own, it is a precursor to angiotensin II, a potent vasoconstrictor. Angiotensin I is converted into angiotensin II by the action of angiotensin-converting enzyme (ACE), which is found in the lungs and other tissues. This conversion is a key step in the renin-angiotensin system and is the target of ACE inhibitors, a class of drugs used to treat high blood pressure and heart failure.

Clinical Significance

Due to its role in the renin-angiotensin system, angiotensin I is implicated in a number of cardiovascular conditions. High levels of angiotensin I can indicate an overactive renin-angiotensin system, which can lead to high blood pressure and other cardiovascular problems. Conversely, low levels of angiotensin I can indicate underactivity of the system, which can lead to low blood pressure and electrolyte imbalances.

Measurement of angiotensin I levels can be used in the diagnosis and management of conditions such as hypertension, heart failure, and kidney disease. In addition, the effect of ACE inhibitors on angiotensin I levels can be used to monitor the effectiveness of these drugs in treating cardiovascular conditions.

See Also

• Renin-angiotensin system
• Angiotensin II
• ACE inhibitors