THE EFFECT OF ORGANOTIN COMPOUNDS ON THE PERMEABILITY OF MODEL BIOLOGICAL-MEMBRANES

The efflux of dimethylarsinic acid (DMA) from liposomes formed from eg g phosphatidylcholine (EPC) is increased when tributyltin chloride (TB T) is added to the extraliposomal compartment; however the addition of monobutyltin trichloride (MBT) slows down the efflux. When the liposo mes are prepared from EPC and organotin compounds, different mechanism s for DMA efflux seem to operate: TBT-EPC liposomes show a mixture of facilitated and passive diffusion; MBT-EPC liposomes show only passive diffusion. The facilitated diffusion of DMA(-) seems to be stopped by the addition of TBT to the extraliposomal compartment. (C) 1997 by Jo hn Wiley & Sons, Ltd.