TABLE 2.
Effect of P4-S on kinetic parameters of NTCP-mediated TC uptake in X. laevis oocytes
Values are calculated from double-reciprocal (Vmax and Km values and efficiency of transport) and Dixon's plots. Specific uptake was calculated as the difference of [3H]TC acid uptake between oocytes expressing NTCP and wild-type oocytes incubated with the same substrate and inhibitor concentrations.
| Inhibitor | Vmax (pmol/10 min/oocyte) | % | Km | % | Efficiency of transport (Vmax/Km) | % | Ki |
|---|---|---|---|---|---|---|---|
| μm | μm | ||||||
| None | 13.2 ± 7.5 | 100 | 10.1 ± 2.1 | 100 | 1.11 ± 0.45 | 100 | |
| PM4-S | 10.7 ± 5.4 | 82 | 38.6 ± 8.9a | 383 | 0.25 ± 0.09a | 23 | 7.7 ± 1.1 |
| PM5-S | 10.9 ± 4.4 | 82 | 40.1 ± 5.4a | 397 | 0.25 ± 0.08a | 23 | 6.4 ± 1.6 |
a p < 0.05, paired t test of efficiency of transport with inhibitor versus efficiency of transport with no inhibitor is shown. Values represent mean ± S.D. of three independent experiments, 10 oocytes/data point/experiment.