EFFECT OF ALUMINUM AND LEAD SALTS ON LIPID-PEROXIDATION AND CELL-SURVIVAL IN HUMAN SKIN FIBROBLASTS

The aim of this study was to see whether aluminum (Al) and lead (Pb) s alts are toxic for cultured human fibroblasts under different experime ntal conditions, in the controllable situation offered by cell culture s. Cell survival and membrane lipid peroxidation served as markers of Al and Pb toxicity. Evaluation of the living cells was carried out usi ng a colorimetric method, the mitochondrial reduction of 1-(4,5-dimeth ylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). Lipoperoxidati on assay was performed on whole cell homogenates by measuring thiobarb ituric acid-reactive substances (TBARS) produced after incubation with ascorbic acid-ferrous sulfate. Al(III) and Pb(II) salts (300 mu M) pr oduce a considerable decrease in cell survival after an exposure perio d of 4 d, evident with the three fetal calf serum concentrations in th e culture media: 2, 5, and 10%. Taking into account in vitro cell agin g, the cytotoxic effects of Al(III) and Pb(II) are greater in senescen t fibroblasts than in young cells. Lead-induced cytotoxicity is higher than Al-induced cytotoxicity. A mechanism that contributes to cellula r toxicity is membrane lipid peroxidation; our results demonstrate tha t Al(III) and Pb(II) ions, 400 mu M, exert an antioxidant-like effect or a pro-oxidant action on cell membranes depending on exposure time. We describe significant increases in TBARS formation associated with t he presence of 400 mu M Al(III) or Pb(II) salts in the culture media. Our study also revealed that these heavy metals induce a cell age-depe ndent action on membrane lipoperoxidation that is greater in senescent fibroblasts and this could have severe consequences for maintenance o f cellular integrity.