angiótensín

Angiotensin is a peptide hormone that plays a crucial role in regulating blood pressure and fluid balance in the body. It is part of the renin-angiotensin-aldosterone system (RAAS), a complex hormonal cascade that influences cardiovascular function. Angiotensin itself is not a single molecule but rather a family of peptides derived from angiotensinogen, a precursor protein synthesized primarily by the liver.

The formation of active angiotensin peptides is a multi-step process. Renin, an enzyme released by the kidneys in response to low blood pressure or low sodium levels, acts on angiotensinogen to produce angiotensin I. Angiotensin I is a relatively inactive decapeptide. Subsequently, angiotensin-converting enzyme (ACE), found mainly in the lungs and blood vessel walls, cleaves angiotensin I to form angiotensin II.

Angiotensin II is the most potent and biologically active form of angiotensin. It exerts its effects by binding to specific receptors, primarily angiotensin II type 1 (AT1) receptors, located on various cells throughout the body. Binding to AT1 receptors triggers a range of physiological responses that lead to an increase in blood pressure. These responses include vasoconstriction (narrowing of blood vessels), which directly elevates blood pressure, and stimulation of the adrenal cortex to release aldosterone. Aldosterone promotes sodium and water reabsorption in the kidneys, further increasing blood volume and pressure. Angiotensin II also influences thirst, heart contractility, and the release of antidiuretic hormone. Due to its significant impact on blood pressure, the RAAS, and particularly angiotensin II, are major targets for pharmaceutical interventions used to treat hypertension and heart failure.