Airway obstruction in asthma: does the response to a deep inspiration matter?

Airway hyperresponsiveness in asthma may not be a problem of too much airwa y smooth muscle strength. Rather, it may be a problem of too little of the factors that oppose muscle shortening. The weight of available evidence see ms to support the idea that loss of the dilating response to a deep inspira tion may play a central role in this process, and that the locus of the res ponse is within the airway smooth muscle cell. Bridge dynamics and plastic reorganization of the smooth muscle cytoskeleton are the focus of this comm entary; how these factors interact and details about underlying mechanisms remain unclear.