Beta-2 receptor stimulation leads to which effects?

Beta-2 receptor stimulation leads to which effects?

• A. Bronchodilation and vasodilation
• B. Increased HR and contractility
• C. Vasoconstriction
• D. Bronchoconstriction

Answer: (A)

Beta-2 receptors are Gs-protein coupled, so their stimulation raises cAMP inside smooth muscle cells. In the airways, higher cAMP lowers intracellular calcium and relaxes bronchial smooth muscle, producing bronchodilation. In vascular smooth muscle of skeletal muscle beds, the same signaling causes relaxation and vasodilation, increasing blood flow to active muscles. This differs from beta-1 effects, which boost heart rate and contractility, and from bronchoconstriction, which is mediated by other receptors like muscarinic (parasympathetic) pathways. So the effects you’d expect with beta-2 stimulation are bronchodilation and vasodilation.

Beta-2 receptors are Gs-protein coupled, so their stimulation raises cAMP inside smooth muscle cells. In the airways, higher cAMP lowers intracellular calcium and relaxes bronchial smooth muscle, producing bronchodilation. In vascular smooth muscle of skeletal muscle beds, the same signaling causes relaxation and vasodilation, increasing blood flow to active muscles. This differs from beta-1 effects, which boost heart rate and contractility, and from bronchoconstriction, which is mediated by other receptors like muscarinic (parasympathetic) pathways. So the effects you’d expect with beta-2 stimulation are bronchodilation and vasodilation.