BIOCHEMICAL CHARACTERISTICS OF LUNGS IN SENESCENCE-ACCELERATED MOUSE (SAM)

This study examined age-related biochemical changes of the lung in an animal model of senile lung, senescence-accelerated mouse (SAM), Bronc hoalveolar lavage (BAL) was performed on two strains of SAM the senesc ence-prone strain (SAM P2) and the senescence-resistant strain (SAM Ri ), as well as on normal ageing C57 black mice (C57BL), aged 1-24 month s, Elastase-like and elastase inhibitory activity of BAL fluid (BALF), glutathione (GSH) and oxidized GSH (GSSG) content both of BALF and lu ng tissue, and oxygen radical generation of free lung cells obtained b y BAL were examined in the three strains of mice, Cell populations did not change throughout the life in SAM strains and C57BL. The elastoly tic activity in SAM was greater than in C57BL, but there was no change with age. Both a decreased content of GSH and an increased oxidation of the GSH in BALF were markedly observed with ageing in SAM P2, In th e lung tissue, the GSSG/GSH ratio in SAM strains was consistently grea ter than that in C57BL, suggesting that the GSH redox cycle of the lun g may be impaired in SAM strains, The oxygen radical generation by fre e lung cells increased with age in all three strains, but the increase was earlier and more pronounced in SAM P2 than in the other two strai ns, In conclusion, an impaired GSH redox cycle and an increased format ion of oxygen radicals are observed in the lungs of SAM with increasin g age.