Figure 3.

(a) Model predictions for static lumen radius as a function of applied transmural pressure for increasing agonist $k_1$. Material parameters are fitted to experimental results of LaPrad et al. (15) (black crosses) (see Methods) to generate the zero agonist case (black curve). Increasing agonist curves (green, blue, red) are consequent model predictions. Dynamic pressure-radius loops are superimposed for i), increasing agonist but fixed $\text{Δ}{P}_{TM}$ centered around $P_{TM}$ = 7.5 cmH₂O (green, blue, and red loops) with color coding corresponding to the agonist level the airway is exposed to and ii), increasing $\text{Δ}{P}_{TM}$ (see Table 1) at fixed agonist level $k_1=0.025$; these are indicated by the three blue loops centered around $P_{TM}$ = 5 cmH₂O. The open magenta circle indicates lumen radius for the unactivated airway at zero transmural pressure. Solid magenta circles indicate lumen radius for the unactivated airway upon application of $P_{TM}=5$ and 7.5 cmH₂O. Transients to the final oscillatory loops are not shown. (b) Effective airway stiffness determined by calculation of the reciprocal of the slope of the static pressure-radius curves in (a) plotted as a function of $P_{TM}$ for increasing agonist. Color-coding is identical to (a). To see this figure in color, go online.