Selective beta blockers act on which receptor?

Selective beta blockers act on which receptor?

• A. Beta-2
• B. Beta-1
• C. Alpha-1
• D. Dopamine

Answer: (B)

Selective beta blockers mainly target beta-1 receptors. These receptors are chiefly located in the heart and in the juxtaglomerular cells of the kidney. Blocking beta-1 reduces heart rate, decreases contractility, and lowers renin release, which together lessen cardiac workload and help lower blood pressure. Because they spare beta-2 receptors in the lungs and vasculature at therapeutic doses, they are less likely to cause bronchospasm or peripheral vasodilation compared with nonselective blockers. The other receptors listed belong to different systems: beta-2 is in smooth muscle of the lungs and vessels, alpha-1 mediates vascular constriction, and dopamine is a different neurotransmitter receptor system not targeted by these drugs.

Selective beta blockers mainly target beta-1 receptors. These receptors are chiefly located in the heart and in the juxtaglomerular cells of the kidney. Blocking beta-1 reduces heart rate, decreases contractility, and lowers renin release, which together lessen cardiac workload and help lower blood pressure. Because they spare beta-2 receptors in the lungs and vasculature at therapeutic doses, they are less likely to cause bronchospasm or peripheral vasodilation compared with nonselective blockers. The other receptors listed belong to different systems: beta-2 is in smooth muscle of the lungs and vessels, alpha-1 mediates vascular constriction, and dopamine is a different neurotransmitter receptor system not targeted by these drugs.