Figure 9.

Effect of selected compounds on concentration-dependent pyridoxine uptake by SLC19A2 and SLC19A3 stably expressed in MDCKII cells. The specific uptake of [³H]pyridoxine by SLC19A2 (A) and SLC19A3 (B) was evaluated at varied concentrations for 3 min at pH 5.5 and 37 °C in the presence of a test compound or in its absence for control. The profiles are transformed into the Eadie-Hofstee format in the right panels. The estimated values of V_max, K_m, and the inhibition constant (K_i) are presented in Table 2. The K_i values of thiamine are also presented in Table 1 for comparison with the IC₅₀ values. Data are presented as the mean ± S.E. (n = 3).