Transport of bile acids in a human intestinal epithelial cell line, Caco-2

Abstract

The transport of taurocholic acid (TA) across Caco-2 cell monolayers was dependent on time in culture and reached a plateau after 28 days, at which time the apical (AP)-to-basolateral (BL) transport was 10-times greater than BL-to-AP transport. The amounts of TA inside the cells following application of 10 nM [ 14C]TA to the AP or BL side of the monolayers (30 min) were approximately equal (54.4 ± 2.7 and 64.6 ± 2.8 fmol/mg protein, respectively). AP-to-BL transport of TA was saturable and temperature-dependent. V max and K m for transport were 13.7 pmol/mg protein per min and 49.7 μM, respectively. The transport of TA had an activation energy of 13.2 kcal·mol −1, required Na + and glucose. AP-to-BL transport of [ 14C]TA was inhibited by the co-administration (on the AP side) of either unlabeled TA or deoxycholate, but it was not reduced by the presence of unlabeled TA on the BL side.