Angiotensiini

Angiotensiini is a group of peptides that play a crucial role in the regulation of blood pressure and fluid balance in the body. These peptides are derived from the renin-angiotensin system, a complex physiological pathway that helps maintain homeostasis. The system begins with the enzyme renin, which is released by the kidneys in response to low blood pressure or low sodium levels. Renin acts on angiotensinogen, a plasma protein, to produce angiotensin I. This peptide is then converted into angiotensin II by the enzyme angiotensin-converting enzyme (ACE) in the lungs.

Angiotensin II is a potent vasoconstrictor, meaning it causes blood vessels to narrow, which increases blood pressure. It also stimulates the release of aldosterone, a hormone that promotes sodium reabsorption and potassium excretion by the kidneys, further contributing to blood pressure regulation. Additionally, angiotensin II can stimulate the release of antidiuretic hormone (ADH) from the pituitary gland, which increases water reabsorption by the kidneys and helps maintain blood volume.

Angiotensiini also plays a role in various physiological processes beyond blood pressure regulation. It can stimulate the proliferation of smooth muscle cells in blood vessels, leading to hypertension and cardiovascular disease. It can also induce the production of reactive oxygen species, which contribute to oxidative stress and inflammation. Furthermore, angiotensin II can stimulate the production of fibrosis, a condition characterized by excessive deposition of extracellular matrix proteins, which can lead to organ damage and dysfunction.

The renin-angiotensin system is a target for various pharmacological interventions, including angiotensin-converting enzyme inhibitors (ACE inhibitors) and angiotensin II receptor blockers (ARBs). These medications are commonly used to treat hypertension, heart failure, and diabetic nephropathy. However, the system also has important physiological functions, and its inhibition can lead to side effects such as cough, angioedema, and hyperkalemia. Therefore, the use of these medications should be carefully considered and monitored by healthcare professionals.