Modulation of MRP1-like efflux activity in human erythrocytes caused by membrane perturbing agents.

The effect of membrane perturbing agents on the efflux (37 degrees C, 60 min) of the fluorescent probe 2', 7'-bis-(carboxypropyl)-5(6)-carboxyfluorescein (BCPCF) from human erythrocytes was studied. Several anionic amphiphiles (detergents) markedly inhibited BCPCF efflux (IC50 < or = 40 microM). Most zwitter-ionic amphiphiles were inefficient inhibitors. Non-ionic and cationic amphiphiles had minor effects or increased efflux. Of the aliphatic inhibitors, C12-homologues were the most efficient. Hexanol, ethanol, methyl-beta-cyclodextrin (MbetaCD) and diamide (+ washing) did not influence BCPCF efflux. It is suggested that amphiphiles affect BCPCF efflux by modulating multi-drug resistance protein 1 (MRP1, ABCC1) activity. A negative charge of amphiphiles is essential for the inhibitory effect, while alkyl chain length modulates inhibition. MRP1-mediated BCPCF efflux appears to be relatively insensitive to non-specific plasma membrane modification.