Which receptor activation leads to bronchodilation?

Which receptor activation leads to bronchodilation?

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

Answer: (D)

Bronchodilation happens when beta-2 adrenergic receptors on bronchial smooth muscle are activated. These receptors are linked to a Gs protein, which boosts adenylyl cyclase activity and raises cAMP levels. Higher cAMP activates PKA, which lowers intracellular calcium and relaxes the smooth muscle, widening the airways. Activation also dampens release of bronchoconstrictive mediators from mast cells, further promoting dilation. Other receptors listed mainly drive constriction or cardiac effects (beta-1 in the heart, alpha-1 and V1 causing vasoconstriction) and do not produce bronchodilation. So, beta-2 receptor activation is what leads to bronchodilation.

Bronchodilation happens when beta-2 adrenergic receptors on bronchial smooth muscle are activated. These receptors are linked to a Gs protein, which boosts adenylyl cyclase activity and raises cAMP levels. Higher cAMP activates PKA, which lowers intracellular calcium and relaxes the smooth muscle, widening the airways. Activation also dampens release of bronchoconstrictive mediators from mast cells, further promoting dilation. Other receptors listed mainly drive constriction or cardiac effects (beta-1 in the heart, alpha-1 and V1 causing vasoconstriction) and do not produce bronchodilation. So, beta-2 receptor activation is what leads to bronchodilation.