Small airway changes in healthy and ovalbumin-treated mice during quasi-static lung inflation

Previously, we developed a synchrotron radiation CT system to evaluate the morphometric changes (length and diameter, D) and small airway compliance (sCaw) of euthanized mice under quasi-static inflation [Sera, T., Uesugi, K., Yagi, N., 2005. Localized morphometric deformations of small airways and alveoli in intact mouse lungs under quasi-static inflation. Respir. Physiol. Neurobiol. 147, 51–63). Using this system, this study compared normal and asthmatic small airways. Ovalbumin-treated mice were used as an asthma model. Compared with the values at functional residual capacity, D of normal and asthmatic small airways (D < 200 μm) increased by 48% and 36% at the end of tidal inspiration. For larger airways (D > 500 μm), the increases were 23% and 20%, respectively. The ratio of the sCaw of asthmatic small airways to that of healthy small airways was 0.57, and the ratio was 0.70 for larger airways. The morphometric changes and sCaw in asthma model mice were significantly lower than those of healthy mice. The differences in sCaw between healthy and asthma model mice were greater for smaller airways.