Norepinephrine, commonly used as a vasopressor in septic shock, primarily activates which receptors?

• A. Beta 2 receptors
• B. Alpha 1 and Beta 1 receptors
• C. Dopaminergic receptors
• D. V1 receptors

Answer: (B)

Norepinephrine works mainly by activating alpha-1 receptors on vascular smooth muscle, causing vasoconstriction that raises systemic vascular resistance and blood pressure. It also stimulates beta-1 receptors in the heart, increasing contractility (and to a lesser extent heart rate), which helps boost cardiac output. This combination is why it’s used as a vasopressor in septic shock—to raise mean arterial pressure and improve organ perfusion. It does not primarily activate beta-2 receptors (which would cause vasodilation), dopaminergic receptors, or V1 vasopressin receptors, so those options aren’t the primary mechanism.