SENSITIVITY OF LUNGS OF AGING FISCHER-344 RATS TO OZONE - ASSESSMENT BY BRONCHOALVEOLAR LAVAGE

Biological effects indicators in bronchoalveolar lavage fluid were stu died in Fischer 344 rats of different ages after exposure to 0.4-0.8 p pm ozone for periods of 2-6 h on a single day or on 4 consecutive days . The magnitude of alveolar protein transudation induced by ozone was not different between age groups, but the interindividual variability of protein changes was higher in senescent (24-mo-old) rats. By compar ison to juvenile (2-mo-old) and adult (9-mo-old) rats, senescent anima ls had higher increases of interleukin-6 (up to 10-fold higher) and N- acetyl-beta-D-glucosaminidase (NAGA; 2-fold higher) in lung lavage aft er ozone. Ascorbic acid was lower in lunes of senescent rats (one-half of juvenile values), and acute ozone exposure brought a further decre ase in lung ascorbate. Whereas alveolar protein transudation was atten uated after ozone exposure on 4 days, persistent elevation of NAGA in senescent rats suggested only partial adaptation. Injection of endotox in did not modify the patterns of effects. Incorporation of O-18-ozone into macrophages and surfactant was not different between age groups, indicating that the magnified biological responses in senescent rats were not dominated by differences in internal dose of ozone. The resul ts indicate that senescent rats respond differently than juvenile and adult rats to lung injury.