Fig. 4.

Kinetics of Na-dependent bile acid uptake in villus cell BBMV from control and MP-treated ileum. A: ³H-taurocholate uptake is shown as a function of varying concentrations of extravesicular taurocholate. Isosmolarity was maintained by adjusting the concentration of mannitol. Uptake for all concentrations was determined at 6 s. As the concentration of extravesicular taurocholate was increased, uptake of taurocholate was stimulated and subsequently became saturated in villus cell BBMV in all conditions. B: Lineweaver-Burk plot of these data with Enzfiter yielded kinetic parameters. Lineweaver Burk plot showed that the K_m remains constant, whereas the V_max changes significantly. The maximal rate of uptake of ³H-taurocholate (V_max) was stimulated by MP. However, the affinity for ³H-taurocholate uptake in BBMV was unaffected in the MP-treated ileum. The data shown are an average of 3 experiments, and each uptake was done in triplicate.