Airway Smooth Muscle as a Target for Asthma Therapy

The precise role of airway smooth muscle in the pathogenesis of asthma remains uncertain. The contraction of airway smooth muscle certainly causes acute narrowing of the airway and airflow obstruction in asthma, and smooth-muscle mass is increased in asthmatic airways. However, whether airway smooth muscle generates sufficient force in vivo to account for the excessive airway obstruction that characterizes asthma is unknown. Abnormalities in the dynamics of contraction,1 in the capacity of smooth muscle to maintain shortening in the face of load fluctuations imposed by tidal breathing,2 or in the capacity to relax3 represent other important mechanisms by which airway . . .