Question

an inhaler used to treat airway constriction in asthma or allergy might contain a drug that
activates nicotinic cholinergic receptors.
activates β₂ adrenergic receptors.
activates muscarinic cholinergic receptors.
activates β₁ adrenergic receptors.
activates β₃ adrenergic receptors.

Explanation:

• Nicotinic cholinergic receptors: Activation leads to skeletal muscle contraction (not relevant for airway dilation).
• β₂ adrenergic receptors: Found in bronchial smooth muscle. Activation causes relaxation, which dilates airways (key for treating airway constriction in asthma/allergy).
• Muscarinic cholinergic receptors: Activation causes bronchoconstriction (opposite of desired effect).
• β₁ adrenergic receptors: Mainly in heart (affects heart rate, not airway dilation).
• β₃ adrenergic receptors: Involved in processes like lipolysis (not airway - related).

Answer:

activates β₂ adrenergic receptors.