How does angiotensin II primarily increase blood pressure?

Angiotensin II primarily increases blood pressure through its potent vasoconstrictive effects on peripheral blood vessels. When angiotensin II is released into the bloodstream, it binds to specific receptors on the smooth muscle cells lining blood vessels, leading to their contraction. This vasoconstriction narrows the diameter of the blood vessels, which increases the resistance to blood flow. As a result, this elevated resistance significantly raises systemic vascular resistance, contributing to higher blood pressure levels.

While stimulating heart rate, increasing renal blood flow, and promoting nitric oxide release can also influence blood pressure, these effects are not as direct or potent as the vasoconstrictive action of angiotensin II. For instance, while increased heart rate can lead to higher cardiac output, it is the vascular resistance caused by angiotensin II that is a more immediate and significant factor in elevating blood pressure.