What effect does angiotensin II have on blood vessels?

Angiotensin II is a potent vasoactive peptide that predominantly causes vasoconstriction, which results in an increase in blood pressure. By binding to specific receptors on vascular smooth muscle, it triggers a contraction of these muscles, narrowing the blood vessels and raising systemic vascular resistance. This mechanism is a critical component of the renin-angiotensin-aldosterone system (RAAS), which the body utilizes to regulate blood pressure and fluid balance.

Additionally, angiotensin II plays a role in stimulating aldosterone secretion from the adrenal glands, further contributing to blood pressure regulation through sodium and water retention. Its ability to cause vasoconstriction directly counteracts any potential blood pressure-lowering mechanisms, reinforcing its role in the elevation of blood pressure under various physiological conditions.