Alpha-1 blockers cause what effect on blood vessels?

Alpha-1 blockers cause what effect on blood vessels?

• A. Vasoconstriction
• B. Vasodilation and reduced BP
• C. Increased heart rate
• D. No effect

Answer: (B)

Alpha-1 receptors on vascular smooth muscle mediate vasoconstriction when stimulated by the sympathetic nervous system. Blocking these receptors prevents that constrictive signal, so the vessels relax and dilate. This vasodilation lowers peripheral vascular resistance and reduces blood pressure. The other options don’t match the direct vascular effect: vasoconstriction would be the opposite, increased heart rate is a reflex/systemic response rather than a direct change in the vessels, and no effect would be incorrect given the receptor blockade.

Alpha-1 receptors on vascular smooth muscle mediate vasoconstriction when stimulated by the sympathetic nervous system. Blocking these receptors prevents that constrictive signal, so the vessels relax and dilate. This vasodilation lowers peripheral vascular resistance and reduces blood pressure. The other options don’t match the direct vascular effect: vasoconstriction would be the opposite, increased heart rate is a reflex/systemic response rather than a direct change in the vessels, and no effect would be incorrect given the receptor blockade.