Norepinephrine activates which receptor combination?

Norepinephrine activates which receptor combination?

• A. Alpha and Beta-1 Agonist
• B. Beta-2 Only
• C. Alpha Only
• D. Alpha, Beta-2 and Beta-3

Answer: (A)

Norepinephrine mainly stimulates alpha receptors (especially alpha-1) and beta-1 receptors, with little to no meaningful activation of beta-2 or beta-3 receptors. This means its physiologic actions include vasoconstriction from alpha-1 and increased cardiac output from beta-1, while Beta-2–mediated effects like bronchodilation or vasodilation are not significant. Therefore, the receptor combination most accurately describes norepinephrine as activating Alpha and Beta-1 receptor sites. The other options would imply substantial beta-2 or beta-3 activity or alpha-only activity, which does not reflect norepinephrine’s receptor profile.

Norepinephrine mainly stimulates alpha receptors (especially alpha-1) and beta-1 receptors, with little to no meaningful activation of beta-2 or beta-3 receptors. This means its physiologic actions include vasoconstriction from alpha-1 and increased cardiac output from beta-1, while Beta-2–mediated effects like bronchodilation or vasodilation are not significant. Therefore, the receptor combination most accurately describes norepinephrine as activating Alpha and Beta-1 receptor sites. The other options would imply substantial beta-2 or beta-3 activity or alpha-only activity, which does not reflect norepinephrine’s receptor profile.