Synchrotron x-ray imaging of pulmonary alveoli in respiration in live intact XXXX .

@entity1 @entity358 @entity19 @entity133
Despite nearly a half century of studies, it has not been fully understood how pulmonary alveoli, the elementary gas exchange units in @entity1 lungs, inflate and deflate during respiration. Understanding alveolar dynamics is crucial for treating @entity1 with @entity358 . In-vivo, real-time visualization of the alveoli during respiration has been hampered by active lung movement. Previous studies have been therefore limited to alveoli at lung apices or subpleural alveoli under open thorax conditions. Here we report direct and real-time visualization of alveoli of live intact @entity19 during respiration using tracking X-ray microscopy. Our studies, for the first time, determine the alveolar size of normal @entity19 in respiration without positive end expiratory pressure as 58    14 (mean    s.d.)  m on average, accurately measured in the lung bases as well as the apices. Individual alveoli of normal lungs clearly show heterogeneous inflation from zero to ~25% (6.7    4.7% (mean    s.d.)) in size. The degree of inflation is higher in the lung bases (8.7    4.3% (mean    s.d.)) than in the apices (5.7    3.2% (mean    s.d.)). The fraction of the total tidal volume allocated for @entity133 is 34    3.8% (mean    s.e.m). This study contributes to the better understanding of alveolar dynamics and helps to develop potential treatment options for @entity358 .
