The organochlorine pesticide lindane interacts with the human erythrocyte membrane

Lindane is an organochlorine pesticide widely used in veterinary and human medicine to treat ectoparasites and pediculosis. Given its lipophilic chara cter lipid-rich membranes are a plausible target of its interaction with li ving organisms. To evaluate its toxic effect on cell membranes lindane was made to interact with human erythrocytes and molecular models of the red ce ll membrane. These consisted in bilayers of dimyristoylphosphatidylcholine (DMPC) and of dimyristoylphosphatidylethanolamine (DMPE), rc:presentative o f phospholipid classes located in the outer and inner monolayers of the ery throcyte membrane, respectively. Experiments by fluorescence spectroscopy s howed that lindane interacted with DMPC large unilamellar vesicles fluidizi ng both its polar head and its acyl chain regions. These results were confi rmed by X-ray diffraction; however, a higher degree of structural perturbat ion was observed in DMPE bilayers. Electron microscopy of human erythrocyte s incubated with lindane revealed that they changed their normal discoid sh ape to cup-shaped stomatocytes. In accordance with the bilayer couple hypot hesis, this result means that lindane inserted in the inner leaflet of the erythrocyte membrane, in agreement with its preferential interaction with D MPE. It is therefore concluded that the toxic effects of the pesticide can be related to its capacity to interact with the lipid moiety of cell membra nes. (C) 1998 Academic Press.