DIETARY RESTRICTION MITIGATES OZONE-INDUCED LUNG INFLAMMATION IN RATS- A ROLE FOR ENDOGENOUS ANTIOXIDANTS

Studies were undertaken to determine whether dietary restriction prote cts against acute pulmonary oxidant challenge, Male F344 rats were ed NIH-31 diet either ad libitum or at restricted levels equal to 75% tha t of ad libitum intake. After 3 wk of dietary adaptation, animals were exposed by inhalation to 2.0 ppm ozone (O-3) for 2 h or chamber air a nd evaluated for cellular and biochemical indices of pulmonary toxicit y. Compared to air controls, bronchoalveolar lavage fluid (BALF) from O-3 exposed ad libitum fed rats contained increased protein (145 versu s 380 mu g/ml), PMN infiltration (0 versus 11%) and fibronectin (45 ve rsus 607 U/ml). Diet restriction abrogated these indicators of pulmona ry inflammation induced by ozone. Binding of O-18(3) to BALF protein a nd cells was significantly decreased in diet restricted rats while BAL F ascorbate and glutathione levels, bill not alpha-tocopherol or urate , were elevated compared to an libitum fed rats. Taken together, these results indicate that dietary restriction affords protection against O-3-induced oxidant toxicity. Protection is mediated partially by incr eases in ascorbate in the fluid bathing the lung surface, thereby prov iding an antioxidant sink which minimizes the ability of O-3 to reach biological targets.