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DEXAMETHASONE ENHANCES PULMONARY INFLAMMATION IN HYPEROXIA-EXPOSED RATS.† 2066

Dexamethasone (DEX) is utilized as an antiinflammatory agent in the treatment of bronchopulmonary dysplasia (BPD). DEX has been shown, however, to accelerate lung injury in hyperoxia-exposed animals. We, therefore, studied the effects of DEX on the lung inflammatory responses of hyperoxia-exposed rats. We administered 1 mg/kg DEX or vehicle ip and placed rats in >95% O2. At 0, 24, and 48 h of hyperoxia-exposure, we collected whole blood for circulating neutrophil (PMN) counts and assessed myeloperoxidase (MPO) activity per PMN. At the same times lung samples for Western blot analysis of E-Selectin and ICAM-1 expression and for lung PMN counts were obtained. DEX treatment increased lung PMN counts independent of hyperoxia-exposure without a change in the expression of E-Selectin or ICAM-1. In addition, DEX-treatment decreased the MPO activity per PMN independent of hyperoxia-exposure. In conclusion, our findings suggest that dexamethasone augments the lung inflammatory response to hyperoxia-exposure by its effects on neutrophils rather than the vascular endothelium. Table

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(Spon. by Charles V. Smith).Supported by NIH grant 5 P30 HD27823-04

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Ramsay, P., Welty, S. DEXAMETHASONE ENHANCES PULMONARY INFLAMMATION IN HYPEROXIA-EXPOSED RATS.† 2066. Pediatr Res 39, 347 (1996). https://doi.org/10.1203/00006450-199604001-02090

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