TABLE 3

Effect of extracellular pH on uptake of [3H]taurocholic acid by HEK293 cells expressing ASBT

NT, not tested.




Uptake


Mock
ASBT
ASBT-Specific Uptake
μl/mg protein
Na+(+) pH 7.4 31.1 ± 0.7 60.2 ± 1.9* 29.0 ± 1.9
pH 5.0 39.5 ± 1.3 59.6 ± 2.4* 20.1 ± 2.4
Na-(-) pH 7.4 28.5 ± 1.7 29.6 ± 1.2 NT

pH 5.0
37.7 ± 0.9
38.5 ± 1.0
NT
  • ASBT-cDNA-transfected or mock cells were preloaded for 20 min at 37°C in the suspension medium (pH 7.4) with or without Na+. Uptake of [3H]taurocholic acid (0.135 μM) was measured for 10 min in the uptake medium at pH 5.0 or 7.4. ASBT-specific uptake of [3H]taurocholic acid was obtained by subtracting the uptake by mock cells from that by OATP-B-cDNA-transfected cells. Each value represents the mean and S.E.M. (n = 3 or 4).

  • * indicates a significant difference from the control (p < 0.05).