Which receptor subtype primarily mediates vasoconstriction and increases peripheral resistance, contributing to higher blood pressure?

Which receptor subtype primarily mediates vasoconstriction and increases peripheral resistance, contributing to higher blood pressure?

• A. Beta-agonists
• B. Alpha 1 receptors
• C. Chemoreceptors
• D. Smooth muscle

Answer: (B)

Alpha-1 receptors on vascular smooth muscle are the main driver of vasoconstriction that raises peripheral resistance and blood pressure. When norepinephrine binds to these receptors, it activates a Gq signaling pathway that stimulates phospholipase C, producing IP3 and DAG. IP3 increases intracellular calcium, and calcium entry further promotes contraction of smooth muscle in the arterioles. This constricts the vessels, raising resistance to blood flow and elevating blood pressure. Beta receptors, especially beta-2, tend to cause vasodilation in many vascular beds and don’t primarily increase peripheral resistance. Chemoreceptors monitor blood chemistry to adjust respiration and sympathetic outflow rather than directly causing arteriolar constriction. Smooth muscle is the tissue that contracts to constrict vessels, but the specific receptor subtype responsible for the vasoconstrictive effect is alpha-1.

Alpha-1 receptors on vascular smooth muscle are the main driver of vasoconstriction that raises peripheral resistance and blood pressure. When norepinephrine binds to these receptors, it activates a Gq signaling pathway that stimulates phospholipase C, producing IP3 and DAG. IP3 increases intracellular calcium, and calcium entry further promotes contraction of smooth muscle in the arterioles. This constricts the vessels, raising resistance to blood flow and elevating blood pressure.

Beta receptors, especially beta-2, tend to cause vasodilation in many vascular beds and don’t primarily increase peripheral resistance. Chemoreceptors monitor blood chemistry to adjust respiration and sympathetic outflow rather than directly causing arteriolar constriction. Smooth muscle is the tissue that contracts to constrict vessels, but the specific receptor subtype responsible for the vasoconstrictive effect is alpha-1.