Fig. 8.

Inhibition of Na⁺-dependent TC initial uptake in suspended human 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 (open symbols; n = 2 livers) from those values in Na⁺-containing buffer (closed symbols; n = 2 livers) in the presence of increasing concentrations of S-sulfone (0.5–300 μM; A) and S-sulfide (0.5–100 μM; C). X and + denote individual data from n = 2 livers in duplicate (B and D). The dotted curve represents the best fit of the sigmoidal inhibitory E_max model to the data by using WinNonlin; the curve shape factor (r) was estimated as 0.6 and 0.9 for S-sulfone and S-sulfide, respectively.