CYTOTOXICITY OF BILIRUBIN FOR HUMAN FIBROBLASTS AND RAT ASTROCYTES INCULTURE - EFFECT OF THE RATIO OF BILIRUBIN TO SERUM-ALBUMIN

The sensitivity of rat brain astrocytes and human fibroblasts in cultu re to unconjugated bilirubin was investigated. Medium containing 6 mu mol/l bilirubin and increasing concentrations of human serum albumin g iving ratios of 0.5-1.5 that resulted in an increase of the free bilir ubin concentrations. The LDH activity in the culture medium was an ind ex of cytolysis and the MTT assay was used as an index of mitochondria l impairment, The ratios producing half-maximum cell lysis after 24, 4 8, and 72h, were 1.1, 0.9 and 0.85, for astrocytes, and 1.2, 0.75 and 0.75, for fibroblasts. Mitochondrial activity decreased after 24 h for ratio = 0.7 and partly recovered at 48 h. Mitochondrial activity was more impaired in fibroblasts than in astrocytes above ratio = 0.7. The cytotoxic effects were linked to the free bilirubin concentration. We conclude that astrocytes are less sensitive to bilirubin cytotoxic ef fects than are fibroblasts. Copyright (C) 1996 Elsevier Science B.V.