Abstract

This study was designed to seek correlations between membrane alterations detected by transport studies and those measured by two biophysical techniques. A group of substituted dithiocarbanilates was found to alter selectively different membrane properties related to permeability and transport. We found a correlation between disruption of a membrane permeability barrier to accumulation of actinomycin D and an enhanced fluorogenic interaction between cells and a dansyl cadaverine probe. Inhibition of facilitated diffusion of nucleosides across the cell membrane was correlated with a more "hydrophobic" cell surface, detected by two-phase aqueous polymer partitioning studies in an "uncharged" system. Inhibition of active transport of a model amino acid, cycloleucine, was correlated with reduced cell-surface and membrane charge, detected by two-phase partitioning studies in a "charged" system. Dithiocarbanilates that caused inhibition of amino acid transport also quenched the fluorogenic cell interaction with dansyl cadaverine, suggesting a more generalized chaotropic drug effect. These findings suggest loci of membrane processes regulating permeability, and of barriers to substrate movement within the cell membrane.