Effects of 60 and 80% oxygen on cell division in lung alveoli of squirrel monkeys

The purpose of this study was to determine the effects on cell division of 60 and 80% oxygen in the lung alveoli of squirrel monkeys. To accomplish this, squirrel monkeys were exposed to 60 and 80% oxygen for up to 8 d. Prior to sacrifice, cells preparing to divide were labeled with tritiated thymidine (3H-TdR). Labeled cells were visualized with autoradiographic techinques, counted with the light microscope, and expressed in terms of a labeling index. In the present study, it was shown that DNA synthesis was not changed by exposure to 60%; however, with exposure to 80% oxygen, cell labeling was well above control levels by 5 d. Analysis of the cell types involved showed an increase in labeling. due to an increase in dividing Type 2 cells. Other cells in the alveolar wall also showed an increase in labeling