Ethanol weakens cytochalasin B binding to the GLUT1 glucose transporter and drug partitioning into lipid bilayers

Ethanol weakens the specific interaction between the human red blood cell (RBC) glucose transporter GLUT1 and the inhibitor cytochalasin B (CB). The chromatographic retention volume of cytochalasin B on stationary phases consisting of GLUT1-containing membranes decreased with increasing ethanol concentration in the eluent. The apparent Kd values for the ethanol–GLUT1 interaction were 0.37, 0.45 and 0.64 M for red blood cells, red blood cell membrane vesicles and proteoliposomes, respectively, all much higher than the Kd values for d-glucose or cytochalasin B interaction with GLUT1. Ethanol also decreased the partitioning of cytochalasin B and drugs into phospholipid bilayers.