Fig. 3.

Tissue traction microscopy reveals an inverse relationship between airway smooth muscle (ASM) contraction and airway lumen area. In response to 10⁻⁶ M histamine followed by 10⁻¹¹ M formoterol, the airways of human precision-cut lung slices (n = 3 obtained from 2 human donor lungs) constricted and then dilated (gray curve) while the ASM contracted and then partially relaxed (black curve). The lumen dilated and the ASM relaxed further immediately after cyclic stretches resembling tidal and deep breathing (amplitude = 4% or 19% cyclic stretch at a frequency of 0.25 Hz for a duration of 5 min each). Data are reported as average and SE.