If a patient experiences acute bronchospasm during an asthma attack, which mechanism underlies the rapid narrowing of airways?

💡 Explanation

Histamine released from mast cells causes rapid bronchoconstriction in asthma because it binds to H1 receptors on bronchial smooth muscle, triggering contraction; therefore, mast cell histamine-mediated smooth muscle contraction explains the bronchospasm, rather than increased CO2, epinephrine vasodilation, or acetylcholine activity.

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