[Histochemical study of a variety of pulmonary alveolar cells: cells containing complex lipid inclusions]

Oxidation of ethanol to acetaldehyde by bronchopulmonary washings: role of bacteria

The synergistic effects of tobacco smoking and alcohol consumption on the incidence of upper respiratory cancer may be linked to their common ability to produce acetaldehyde, an irritant and potential mutagen. Since alcohol consumption in most individuals results in very low concentrations of acetaldehyde in the blood, we determined whether bronchopulmonary cellular components are capable of oxidizing ethanol to acetaldehyde. We found that significant production of acetaldehyde occurred in vitro after incubation of human bronchopulmonary washings with 25 mM ethanol. Acetaldehyde production was increased in active smokers and related to microorganisms in the bronchopulmonary tract. It was abolished by preincubation of the washings with antibiotics and was reproduced in vitro with Streptococcus pneumoniae. Normal pulmonary cells in bronchopulmonary washings did not produce acetaldehyde from ethanol.

The mode of secretion of the Clara cell in rat bronchiole: a freeze-fracture study

Freeze-fracture was used to study the nonciliated epithelial (Clara) cell of rat bronchiole. En face views of the P face of the luminal cell membrane reveal particle-free bulging and circular depressions at the presumptive sites of the membrane fusion between the cell membrane and secretory granule membrane. Cross fracture views of the cytoplasm reveal the membraneous continuity from the secretory granule to the luminal cell membrane with the decrease of the intramembrane particles. These findings indicate that the mode of secretion of the Clara cell is a merocrine secretion by exocytosis.