Acute and Subacute Effects of Injury on the Canine Alveolar Septum (1)
The acute and subacute changes in lung remodeling resulting from proteolytic agents which produce severe pulmonary emphysema are not well understood. A canine model was developed in which severe emphysema is produced in only one lung, allowing survival of the animal so that such changes can be studied.
In an earlier report using this model,2 we described primarily the ultrastructural changes occurring on the alveolar surface of pulmonary alveoli exposed to papain. We have since extended these studies, focusing in this report on the alveolar septum. We wanted to ascertain in particular, what, if any, were the relationships between gaps in the connective tissue matrix of the alveolar septum and alveolar macrophages, as well as epithelial cells, following severe proteolytic injury. Since serial sections of the whole circumference of alveoli from normal human lungs had proved to be fruitful in bringing to light relationships between alveolar macrophages, septal gaps and type 2 cells, which had not been previously appreciated or reported, we applied similar techniques, ie, serial sections of whole alveoli, to a reexamination of the animal specimens from the earlier work. buy levaquin online
The evidence for a possible role for the alveolar macrophage in the pathogenesis of emphysema is quite suggestive. It includes the finding of increased numbers of alveolar macrophages, as well as increased elastase activity in macrophages obtained from smokers’ lungs. It also includes the experimental induction of emphysema by the instillation of either elastase or homogenates of alveolar macrophages into the lung, as well as enhancement of papain-induced emphysema by activated alveolar macrophages.