The effect of ethchlorvynol on pulmonary ultrastructure in dogs.

The ultrastructure of alveolar septae in dogs is investigated at times ranging from 30 seconds to 60 minutes after intravenous injection of ethchlorvynol (Placidyl). Pulmonary edematous fluid first appears in alveolar spaces 5 minutes after injection and becomes progressively more prominent with increasing time. Alveolar septae are initially somewhat fibrotic, and subsequently, most interstitial spaces become swollen and hydrated. Vesicles in endothelial cells increase with postinjectional time, and they seem to form channels or pores interconnecting capillaries and interstitial spaces. Similar vesicles in epithelial cells (Type 1) show an increase after 30 minutes, and they also seem to form channels or pores interconnecting interstitial spaces and the alveolus. Vesicles, whether in endothelial or epithelial cells, contain a flocculent filamentous material similar to plasma protein and the filamentous proteinaceous material in edematous fluid in alveolar spaces. Ethchlorvynol injection rapidly induces a non-hemodynamic form of pulmonary edema. Since cell junctions of both endothelial and epithelial cells remained intact, it is proposed that transalveolar transport of edematous proteinaceous fluid is mediated by means of endothelial and epithelial vesicles.