Airway Smooth Muscle (ASM)

Airway smooth muscle (ASM) is a specialized smooth muscle tissue within the respiratory tract walls, from the trachea to the bronchioles. It regulates airway caliber by contracting or relaxing, controlling airflow resistance and ventilation distribution. ASM dysfunction, including hypertrophy/hyperplasia and hyperresponsiveness, plays a central role in asthma and other respiratory diseases. Targeting ASM is a primary therapeutic strategy for these conditions.

Other names

Bronchial Smooth MuscleTracheal Smooth Muscle

Drugs targeting ASM primarily induce bronchodilation by relaxing the smooth muscle. β2-agonists stimulate β2-adrenergic receptors, increasing intracellular cAMP and causing smooth muscle relaxation. Anticholinergics block muscarinic receptors, preventing acetylcholine-mediated constriction. Anti-inflammatory drugs reduce inflammation that contributes to ASM hyperreactivity.