Effects of Smoke Inhalation on Expressions of Pulmonary Surfactantassociated Protein A in Rats' Lung Tissues

Aim: To evaluate the expressional alterations of pulmonaryassociated protein A (SPA) in lung tissues after smoke inhalation. Methods: Following the use of a rat smoke inhalation injury model and the immunohistochemical technique, the present study was designed to determine the dynamic changes of expressions of SPA in lung tissues. The concomitant changes of arterial blood gas levels, lung water volume, pathomorphology of lungs and the activity of elastase in bronchoalveolar lavage fluid (BALF) were also observed. Results: The animals showed acute respiratory failure and pulmonary edema after smoke inhalation. The pathomorphologically serious lung damage was also found. The elastase activity in BALF increased significantly. Along with the onset and development of acute lung injury, not only the expressions of intra and extracellular SPA decreased markedly, but also the immunostained alveolar type Ⅱ cells reduced dramatically. There was a significant correlation between the decrease of integral optical density of positive SPA immunostain in per unit alveolar area and the increase of elastase activity in BALF. Conclusion: The expressions of SPA in lung tissues decrease significantly, and it may contribute considerately to pulmonary surfactant system dysfunction and respiratory failure after smoke inhalation injury.