Dietary restriction mitigates ozone-induced lung inflammation in rats: A role for endogenous antioxidants

Studies were undertaken to determine whether dietary restriction protects against acute pulmonary oxidant challenge, Male F344 rats were ed NIH-31 diet either ad libitum or at restricted levels equal to 75% that 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 and evaluated for cellular and biochemical indices of pulmonary toxicity. Compared to air controls, bronchoalveolar lavage fluid (BALF) from O-3 exposed ad libitum fed rats contained increased protein (145 versus 380 mu g/ml), PMN infiltration (0 versus 11%) and fibronectin (45 versus 607 U/ml). Diet restriction abrogated these indicators of pulmonary inflammation induced by ozone. Binding of O-18(3) to BALF protein and cells was significantly decreased in diet restricted rats while BALF 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 increases in ascorbate in the fluid bathing the lung surface, thereby providing an antioxidant sink which minimizes the ability of O-3 to reach biological targets.