FIG. 3.

Uptake of [¹⁴C]cefixime into Caco-2 cells as a function of substrate concentration. Transport of 0.05 to 5 mM cefixime was measured at pH 5.0 either in the absence of nifedipine (control; ○) or in the presence of 100 μM nifedipine (•). Transformation of the transport rates according to Eadie-Hofstee (inset) revealed K_m and V_max values of 1.9 ± 0.2 mM and 36.2 ± 2.7 nmol · cm⁻² · 30 min⁻¹, respectively, in control cells and 1.8 ± 0.2 mM and 60.6 ± 5.9 nmol · cm⁻² · 30 min⁻¹, respectively, in nifedipine-treated cells.