LIPID-PEROXIDATION AND DISINTEGRATION OF THE CELL-MEMBRANE STRUCTURE IN CULTURES OF RAT LUNG FIBROBLASTS TREATED WITH ASBESTOS

Rat lung fibroblasts were cultured for 24 and 48 h with UICC standard reference asbestos samples of amosite, crocidolite or Canadian chrysotile at various concentrations, and thiobarbituric acid-reactive substances (TBARS) in the media and the cells were measured. Tests by the trypan blue dye-exclusion method showed that cell viability was 80 +/- 5% (mean +/- SD) and 71 +/- 6% when cultured for 48 h in the presence of 500 mug ml-1 of amosite and crocidolite, respectively, but was not affected by chrysotile. In cultures for 24 and 48 h, both chrysotile and crocidolite at > 250 mug ml-1 significantly increased TBARS in the medium, whereas amosite did so at > 500 mug ml-1. TBARS in the cells was not increased significantly by chrysotile at any concentration in the cultures for 24 and 48 h, but crocidolite at > 250 mug ml-1 significantly increased TBARS in the cells when cultured for 24 or 48 h. Although amosite at all concentrations tested did not increase significantly TBARS in the cells of the 24-h culture, it did increase TBARS significantly in the cells when cultured for 48 h at a concentration of 500 mug ml-1 amosite. The increases of TBARS in media of the cultures with asbestos were accompanied by increases of lactate dehydrogenase (LDH) activity in the media, indicating the leakage of the enzyme from the cell into the media. The activity of LDH and the amount of TBARS showed a good correlation with each other, with a significant correlation coefficient value of 0.655. Thus, the amount of TBARS produced during the culture seemed to change, depending on both the asbestos concentration and the inherent properties. The findings suggest that when certain types of asbestos are cultured with rat lung fibroblasts the cell membranes are peroxidized to cause disintegration of the membrane structure, followed by leakage of cellular LDH into the medium.