Experimental study of pulmonary emphysema in rats exposed to coal dust and papain: effects on the infrastructure and the cell dynamics.

Experimental lesions of emphysema were produced in SPF rats after laryngotracheal injection of papain and coal dust. The infrastructural changes were investigated a different intervals. The lesions observed are progressive, characterized by atrophy and ruptures of the interalveolar septa, and the disappearance of pneumocytes II. Passage through the septa of mineral particles is enhanced and total dust clearance seems to be increased. The results are discussed in the light of alveolar clearance studies using Fe-59 and surface tension measurements on pulmonary washings.