angiotensin-mediated vasoconstriction involved in regulation of systemic arterial blood pressure

Definition

Target type: biologicalprocess

The decrease in blood vessel diameter as a result of the release of angiotensin into the blood stream. [GOC:mtg_cardio, GOC:pr, ISBN:0721643949]

Angiotensin II, a potent vasoconstrictor peptide, plays a crucial role in regulating systemic arterial blood pressure. Its action is initiated when renin, an enzyme produced by the kidneys, cleaves angiotensinogen, a protein synthesized in the liver, to generate angiotensin I. Angiotensin-converting enzyme (ACE), primarily found in the lungs, then converts angiotensin I to angiotensin II.

Angiotensin II exerts its vasoconstrictive effects through two primary mechanisms:

1. **Direct vasoconstriction:** Angiotensin II binds to its receptors, specifically the angiotensin II type 1 receptor (AT1R), located on vascular smooth muscle cells. This binding activates a signaling cascade that leads to an increase in intracellular calcium levels. Elevated calcium triggers contraction of the vascular smooth muscle, resulting in vasoconstriction.

2. **Indirect vasoconstriction:** Angiotensin II also stimulates the release of other vasoconstrictors, such as norepinephrine from sympathetic nerve endings. This further contributes to narrowing of blood vessels.

Furthermore, angiotensin II stimulates the adrenal glands to release aldosterone, a hormone that promotes sodium retention and potassium excretion by the kidneys. This sodium retention contributes to increased blood volume and, consequently, elevated blood pressure.

Angiotensin II also directly acts on the kidneys to reduce renal blood flow and glomerular filtration rate, further contributing to blood pressure elevation.

In summary, angiotensin-mediated vasoconstriction is a complex process involving direct and indirect mechanisms that contribute to the regulation of systemic arterial blood pressure. This process is tightly regulated by the renin-angiotensin-aldosterone system (RAAS), ensuring appropriate blood pressure maintenance.'
"

Proteins (1)

Compounds (1)