Fig. 5.

Inhibition of Na⁺-dependent TC initial uptake in suspended rat hepatocytes by S-sulfone (A and B) and S-sulfide (C and D). Na⁺-dependent [³H]TC initial uptake (1 μM, 60 nCi/ml, 30 s) was determined by subtracting [³H]TC uptake in Na⁺-free buffer (○) from [³H]TC uptake in Na⁺-containing buffer (●) in the presence of increasing concentrations of S-sulfone (0.5–100 μM; A) and S-sulfide (0.5–100 μM; C). Symbols and error bars represent the mean ± S.D. of n = 1–3 livers in duplicate. The dotted curve represents the best fit of the sigmoidal inhibitory E_max model to the data by using WinNonlin (B and D); the curve shape factor (r) was estimated as 0.31 ± 0.04 and 0.81 ± 0.09 for S-sulfone and S-sulfide, respectively.