Stereologic evaluation of granular pneumocyte lamellar bodies in different species.

Lamellar bodies in individual pulmonary glanular pneumocytes in the species examined (mouse, rat, rabbit, and dog) have virtually the same volume density with respect to the cytoplasmic volume as estimated by stereological techniques. The surface-to-volume ratio for these structures also fail to show any interspecies variation in these species.

Lung oxygen consumption and mitochondria of alveolar epithelial and endothelial cells.

We examined oxygen consumption by lung slices and measured the volume density of mitochondria of granular pneumocytes, alveolar type I cells, and alveolar capillary endothelial cells in several species. We found that lung oxygen consumption (mu-1 02 times h-1 times mg DNA-1) varies inversely with the log of animal body weight and with the species alveolar diameter and directly with the species respiratory rate. The volume density of granular pneumocyte mitochondria show a direct linear correlation with the lung's oxygen consumption and the species respiratory rate, and an inverse linear correlation with the species alveolar diameter.

Influence of cycloheximide on the lung.

We examined the time course of the influence of cycloheximide on descending pressure-volume curves of excised lungs and on protein and lecithin synthesis and oxygen consumption by lung slices. We also looked at the influence of cycloheximide on granular pneumocyte ultrastructure. Excised lungs from cycloheximide-treated animals are more compliant than controls.

Intraspecies differences in lung metabolism and granular pneumocyte mitochondria.

The authors used waltzing and nonwaltzing mice to examine granular pneumocyte mitochondria and lung oxygen consumption and protein synthesis. They found that the oxygen consumption of lung slices from waltzing mice is higher than that of lung slices from nonwaltzing mice. The volume density of granular pneumocyte mitochondria is higher in waltzing than nonwaltzing mice as is their number per 100 mum-3 of cytoplasm.

Adaption to hyperoxia. Influence on protein synthesis by lung and on granular pneumocyte ultrastructure.

We studied the influence of prolonged exposure to hyperoxia (O(2) > 98%) on protein synthesis and on the ultrastructure of the granular pneumocyte. To study protein synthesis, as indicated by l-[U-(14)C]-leucine incorporation into protein, lung slices were incubated with radioactive leucine and a surface-active fraction was obtained by ultracentrifugation of lung homogenates. We found that, following an initial depression in protein synthesis after 48 h of hyperoxia, protein synthesis in rats exposed to oxygen for 96 h rose to greater than control levels.

Hyperoxia: a stereologic ultrastructural examination of its influence on cytoplasmic components of the pulmonary granular pneumocyte.

We used the technique of lineal analysis to study the influence of 48 h of hyperoxia on cytoplasmic organelles of pulmonary granular pneumocytes with particular reference to their lamellar bodies. We undertook this study because lamellar bodies are considered to be storage granules for pulmonary surfactant and because we had found that hyperoxia decreased [(14)C]leucine incorporation into protein of a surface-active lung fraction. We found that for lamellar bodies the percent cytoplasmic volume was 12.