title: The effect of membrane surface potential on the permeability of anionic compounds across the apical membrane in human intestinal epithelial (Caco-2) cells.
abstract: The effect of membrane surface potential of the apical side on the intracellular uptake of ionic compounds was investigated using the human colon adenocarcinoma cell line (Caco-2). The transepithelial transport of indolepropionic acid and tryptamine was consistent with the uptake behavior shown by rat intestinal brush-border membrane (BBM) vesicles. Imipramine, which diminished the negative charge of the membrane surface (for both Caco-2 and BBM), acted to increase the uptake of the anionic compounds, indolepropionic acid and ceftibuten, and to decrease that of tryptamine (cationic compound) by both the Caco-2 monolayer and the intestinal BBM vesicles at a pH of 7.5. These results suggest that the effects of membrane surface potential on the permeability of ionic compounds were detectable on the Caco-2 cell line as well as the BBM vesicles. On the other hand, the inhibition of H(+)-linked transport and the stimulation of the surface charge-regulated uptake of ceftibuten have occurred simultaneously on the Caco-2 cell line in the presence of imipramine. It seems that the membrane surface charge (negative) plays an important role in the transport process of ionic compounds across the intestinal epithelium.
authors.affiliation: Department of Pharmacy, Hokkaido University Hospital, School of Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Iseki
authors.forename: K
authors.initials: K
authors.lastname: Kaido
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: M
authors.initials: M
authors.lastname: Sugawara
authors.forename: K
authors.initials: K
authors.lastname: Miyazaki
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000585:Aminacrine / Q000737:chemistry; D000818:Animals; D018938:Caco-2 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007099:Imipramine / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D017136:Ion Transport; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000585:Aminacrine; D000255:Adenosine Triphosphate; D007099:Imipramine