THE KINETICS OF UPTAKE OF 5-FLUOROURACIL BY RAT LIVER

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Abstract
1 Slices of rat liver weighing 15–30 mg were incubated at 37°C in 5-fluorouracil (5-FU) solution. 2 The 5-FU taken up was measured by high pressure liquid chromatography. 3 Uptake of 5-FU was found to approximate to Michaelis-Menton kinetics with the values of Kt and Vmax equal to 15.39 mmol l−1 and 1.96 μmol g−1 min−1 respectively. 4 Transport of 5-FU was saturable with the uptake being much greater in the non-fasting rats. 5 Intracellular concentration of 5-FU after 24 min incubation approached but did not significantly exceed that in the extracellular fluid. 6 Enzymatic destruction of 5-FU at 2 min was negligible but substantial after a long incubation period. 7 2,4-Dinitrophenol was found to inhibit transport of 5-FU significantly. 8 Results suggested that the mechanism of uptake of 5-FU by rat liver is an energy requiring process.