An oligopeptide hormone in the blood that causes blood vessels to constrict, and drives blood pressure up. It is part of the renin-angiotensin system.
A substance in the blood (formed by renin) that is a powerful constrictor of arteries and arterioles.
A polypeptide which affects blood pressure by causing vasoconstriction and increasing extracellular volume.
The natural substrate for renin. It is an α2-globulin (a glycoprotein) synthesized in the liver and transported to the kidney in an inactive form, angiotensinogen. It is converted to angiotensin I and then to angiotensin II in the kidney. Angiotensin II stimulates the production of aldosterone and also functions as a vasoconstrictor in the circulatory system raising blood pressure.
Chemical in the blood that causes blood vessels to become narrowed; also called angiotonin.
A physically inactive hormone that is a converted into angiotensin II by the lungs.
A hormone that causes blood vessels to constrict and raises blood pressure. Medications that prevent the formation of angiotensin, known as angiotensin-converting enzyme (ACE) inhibitors, lower blood pressure and reduce the workload on the heart. They are commonly used in the treatment of congestive heart failure and high blood pressure. Another class of medications, the angiotensin-receptor blocking agents, block the effect of angiotensin and have effects similar to those of ACE inhibitors.
A protein in the blood, derived from a plasma protein and released by the action of an enzyme (renin) from the kidneys, that causes an increase in the output of ‘aldosterone from the adrenal cortex. Angiotensin is also capable o causing constriction of blood vessels, thus raising blood pressure.
Angiotensin is a peptide that occurs in two forms: I and II. The former results from the action of the enzyme, renin on alpha globulin (a protein) produced by the liver and passed into the blood. During passage of the blood through the lungs, angiotensin I is converted into an active form, angiotensin II, by an enzyme. This active form constricts the blood vessels and stimulates the release of two hormones — vasopressin and aldosterone —which raise the blood pressure.
A vasopressor produced when renin is released from the kidney. Renin is formed by the juxtaglomerular apparatus of the kidney.
The regulation of blood pressure involves two interconnected proteins. The first protein, called angiotensin I, remains inactive and is produced when renin, an enzyme synthesized by the kidneys, acts upon the substance angiotensinogen. Subsequently, angiotensin I undergoes conversion to its active form, known as angiotensin II, facilitated by the action of angiotensin-converting enzyme.
The presence of angiotensin II triggers a constriction of the narrow blood vessels within tissues, leading to an elevation in blood pressure. Additionally, it stimulates the secretion of aldosterone, a hormone released by the outer part of the adrenal glands known as the adrenal cortex. The release of aldosterone further contributes to an increase in blood pressure.
Specific kidney disorders have the potential to elevate the production of angiotensin II, leading to hypertension or high blood pressure. To address hypertension, medical intervention often involves the administration of ACE inhibitor drugs, which work to diminish the formation of angiotensin II. Alternatively, angiotensin II antagonists can also be employed as a treatment option.