Figure 2: From [60]. Airway narrowing (Δvolume, %) to acetylcholine (ACh) in human bronchial segments. ACh dose-response curves were constructed from measurements of airway narrowing under static conditions (Static, 5 cmH2O) and during fixed transmural pressure cycles simulating tidal (5 to 10 cmH2O at 0.25 Hz) and deep inspiration (DI, 5 to 30 cmH2O). The dynamic pre-DI curve represents airway narrowing before the onset of DI; dynamic DI 0 s, the airway narrowing measured immediately after DI; dynamic DI 60 s, the airway narrowing measured 1 min after DI. DI produced an immediate reduction in maximal airway narrowing ( ) but not sensitivity. The effects of DI were largely ablated after 1 min. Airway narrowing under static conditions was not different to that prior to DI, suggesting that tidal oscillations alone did not regulate airway narrowing. Values are means ± SE ( ).