Abstract
ABSTRACT: We have examined the effect of dexamethasone on the metabolism of pulmonary surfactant in normal and hyperoxia-treated rats. The relative abundance of the surfactant-specific apoprotein A (SP-A) mRNA in lung tissues and the contents of disaturated phosphatidylcholine (DSPC) and SP-A were measured in bronchoalveolar lavage fluids and in lung tissues in 4-wk-old rats exposed to room air or >90% oxygen for 7 d with or without simultaneous treatment with dexamethasone (0.5 mg/kg body wt for 7 d). The relative abundance of the SP-A mRNA was marginally increased by hyperoxia (1.3-fold over controls). Dexamethasone increased the relative abundance of the SP-A mRNA to a level comparable to that with hyperoxia treatment (1.5-fold over controls). In lavage fluids, the contents of DSPC and SP-A were increased by 4− and 6-fold over controls by hyperoxia, respectively, but they were increased only by 2-fold by dexamethasone. In lung tissues, the contents of DSPC and SP-A were increased by 3− and 2-fold over controls by hyperoxia, respectively. These values in lung tissues in the air-exposed rats were not significantly increased by dexamethasone. In hyperoxia-treated rats, dexamethasone did not significantly affect the relative abundance of the SP-A mRNA level and the contents of DSPC and SP-A in lavage fluids and lung tissues. These results indicate that mechanisms other than increased synthesis of SP-A are involved in hyperoxia-induced SP-A accumulation and that dexamethasone does not affect the abnormal accumulation of pulmonary surfactant induced by hyperoxia.
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Ohashi, T., Takada, S., Motoike, T. et al. Effect of Dexamethasone on Pulmonary Surfactant Metabolism in Hyperoxia-Treated Rat Lungs. Pediatr Res 29, 173–177 (1991). https://doi.org/10.1203/00006450-199102000-00014
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DOI: https://doi.org/10.1203/00006450-199102000-00014