[The uptake characteristics of 5-fluorouracil in the Caco-2 model system]

The uptake characteristics of 5-fluorouracil in the Caco-2 model system were studied. The uptake of 5-fluorouracil was determined at different pH and concentrations, and in the presence of various inhibitors. The results indicated that the uptake of 5-fluorouracil was the best at pH 6.0. The rate of uptake was saturable with a Km of 24 mmol.L-1, and a Vmax of 20.9 nmol.min-1.mg-1 protein. The uptake was inhibited by noncompetitive inhibitors such as NaCN, ouabain, and dipyridamole. The uptake was also inhibited competitively by analogous compounds such as uracil, thymine, and uridine (but not by hypoxanthine). In conclusion, the evidence suggests that 5-fluorouracil was transported by uracil carrier in Caco-2 cells.