This study was carried out to confirm the hypothesis that an autoperfused heart-lung preparation provides a favorable situation to analyze the dynamics of the biosynthesis of alveolar surface-active material, because the model did not produce any significant changes in the structure of the lung. Light and electron microscopy confirmed the absence of pulmonary lesions throughout the whole time of perfusion. A relevant finding was the periodic delamellation of the type II pneumocytes observed ultrastructurally, which coincided with the data obtained from the study on 14C-glycerol-3-phosphate and 3H-palmitic acid incorporation into total lipids and phosphoglycerides from lung tissue. This confirmed that the biosynthesis of pulmonary surfactant is rhythmic and periodic. From a structural point of view, the results suggest that the autoperfused heart-lung preparation constitutes a useful method for the in vivo metabolic study of the isolated lung.
Animals Cytoplasm