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We quantified the effects of airway wall remodeling upon airway smooth muscle (ASM) shortening. Isolated ASM from sheep was attached to a servo-controller that applied a physiologic load. This load could be altered to reflect specified changes of airway wall geometry, elasticity, parenchymal tethering, transpulmonary pressure (P_L), and fluctuations in P_L associated with breathing. Starting at a reference length (L_ref), ASM was stimulated with acetlycholine and held at constant P_L of 4 cm H₂O for 2 h. When all compartments were thickened to simulate the asthmatic airway but P_L was held fixed, ASM shortened much more than that in the normal airway (to 0.52 L_ref versus 0.66 L_ref). When breathing with deep inspirations (DIs) was initiated, within the first three DIs the ASM in the normal airway lengthened to 0.84 L_ref, whereas that in the asthmatic airway remained stuck at 0.53 L_ref. Thickening of the smooth …