angiotensín

Angiotensin is a peptide hormone involved in the regulation of blood pressure and fluid balance within the body. It plays a central role in the renin-angiotensin-aldosterone system (RAAS), a key physiological pathway that helps maintain homeostasis. The process begins with the enzyme renin, secreted by the kidneys in response to low blood pressure or sodium levels, which cleaves angiotensinogen—a protein produced by the liver—into angiotensin I. This inactive peptide is then converted into angiotensin II by the angiotensin-converting enzyme (ACE), primarily in the lungs.

Angiotensin II is a potent vasoconstrictor, meaning it narrows blood vessels, thereby increasing blood pressure. It also stimulates the release of aldosterone from the adrenal cortex, promoting sodium and water reabsorption in the kidneys, which further raises blood pressure and volume. Additionally, angiotensin II enhances the release of antidiuretic hormone (ADH), reducing urine output and conserving water. It also stimulates thirst, contributing to fluid retention.

Beyond its role in blood pressure regulation, angiotensin II influences cardiac function, inflammation, and tissue remodeling. Chronic activation of the RAAS has been linked to hypertension, heart failure, and kidney disease. Medications such as ACE inhibitors and angiotensin receptor blockers (ARBs) are commonly used to counteract excessive angiotensin activity by blocking its formation or effects, thereby lowering blood pressure and reducing cardiovascular risk.

Angiotensin II also has effects on the adrenal medulla, promoting the release of adrenaline and noradrenaline, which further contribute to vasoconstriction and increased heart rate. Its role in cell growth and fibrosis makes it relevant in pathological conditions like atherosclerosis and diabetic nephropathy. Research continues to explore its broader implications in physiology and disease.