INTERSPECIES COMPARISON OF RAT AND HAMSTER ALVEOLAR MACROPHAGE ANTIOXIDATIVE AND OXIDATIVE CAPACITY

Generation of oxidants has been implicated in lung injury and disease caused by a variety of inhaled agents such as ozone, particles, and mi neral fibers. Antioxidants in the pulmonary system presumably provide the initial defense against such oxidants. We designed the present stu dy to assess the oxidative and antioxidative capacity of alveolar macr ophages (AM) from rats and hamsters. These two laboratory animal speci es commonly used in biomedical research are well known for their dispa rate response to pulmonary irritants/toxicants. AM from CD rats and Sy rian golden hamsters were obtained by bronchoalveolar lavage. We asses sed AM antioxidant levels by measuring the catalase and superoxide dis mutase (SOD) activity and the intracellular concentrations of total gl utathione, ascorbic acid, and alpha-tocopherol. We determined the AM o xidative capacity by assessing the ability of AM to oxidize extracellu lar glutathione (GSH) and to release superoxide anions. There were no significant differences in the intracellular antioxidant levels, excep t for catalase activity that was significantly (p<0.05) higher in hams ter AM than in rat AM. However, AM oxidative capacity was markedly dif ferent between the two species studied. The amount of spontaneous and phorbol myristate acetate (PMA)-induced GSH oxidation was about 5-fold higher in rat AM than in hamster AM, whereas the PMA-induced superoxi de anion release did not differ significantly between the two rodents. in summary, our data suggest that species variation exists between th e oxidative capacity of rat and that of hamster AM. Whereas the oxidat ive capacity of hamster AM appears to be based mainly on the formation of reactive oxygen species, it is suggested that rat AM possess an ad ditional oxidative system.