Cellular influx of sulfobromophthalein by the biliary epithelium carcinoma cell line Sk-Cha-1 reveals kinetic criteria of a carrier-mediated uptake mechanism.
Cellular uptake of the cholephilic organic anion sulphobromophthalein (BSP) by the human biliary epithelium carcinoma cell line Sk-Cha-1 was examined at 37 degrees C. In confluent monolayer cultures the cellular influx rate of increasing concentrations of [35S]BSP followed saturation kinetics with a Km value of 18 microM and a Vmax value of 243 pmol.min-1.mg protein-1. Uptake of [35S]BSP was competitively inhibited by the presence of bilirubin diglucuronide, but not by taurocholate or cholate. Furthermore, uptake was temperature dependent with maximal cellular influx rates at 37 degrees C.
Stremmel
W
W
Department of Internal Medicine, Heinrich Heine University, Düsseldorf, F.R.G.
Falbrede
J
J
Diede
H E
HE
Elsing
C
C
D001661:Biliary Tract Neoplasms / Q000378:metabolism*; D001663:Bilirubin / Q000031:analogs & derivatives / Q000494:pharmacology; D001667:Binding, Competitive; D001693:Biological Transport, Active / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D013448:Sulfobromophthalein / Q000378:metabolism*; D013696:Temperature; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D013448:Sulfobromophthalein; C019270:bilirubin diglucuronide; D001663:Bilirubin