RESUMO
The effects of a variety of detergents (non-ionic, ionic and bile derivatives) on B16 melanoma cells have been examined. Two main effects can be clearly differentiated: loss of cell viability and cell lysis. Under our conditions, cell-surfactant interaction is highly dependent on the nature of the amphiphile (more specifically, on its critical micellar concentration). Loss of cell viability occurs at surfactant concentrations below the critical micellar concentration, i.e. the incorporation of detergent monomers into the cell membranes is enough to impair their barrier function, so that Trypan Blue is no longer actively secreted outside the cell. On the other hand, cell lysis only occurs at or near the critical micellar concentration of the detergent, i.e. when the bilayer-micelle transition may take place. Comparative studies using B16 cells and phospholipid vesicles indicate that the amount of detergent required to induce cell lysis is the same that produces disruption of the lipid bilayer. Thus, our results suggest that membranes are the primary target for the toxicologic effects of surfactants on cells. Moreover, they provide a rationale for the interpretation of other studies in this field: previous results from different laboratories are shown to fit very well our data.
