Differential expression of cholangiocyte and ileal bile acid transporters following bile acid supplementation and depletion

Figure 1 Q-RPA data demonstrating down-regulation of ASBT and t-ASBT message following TCA feeding and up-regulation of their expression following CY feeding in cholangiocytes. Bar graphs demonstrating ASBT and t-ASBT mRNA expression, in which 40 μg total cellular RNA isolated from cholangiocytes obtained from rats fed regular chow (C), 1% TCA or 5% CY incorporated diets were used. Densitometric values shown here are expressed as mean ± SE and represent 3 feeding studies in which 30 rats in total were analyzed per group (^aP < 0.05).

Figure 2 Effect of TCA and CY feeding on the expression of ASBT and t-ASBT protein in cholangiocytes. Bar graphs show-ing densitometric ratios of ASBT and t-ASBT standardized to β-actin in PNS fractions of freshly isolated cholangiocytes from rats fed control (C), 1% TCA or 5% CY incorporated diet. A 80 μg for ASBT and 120 μg for t-ASBT PNS protein were sub-jected to SDS-PAGE, immunoblotted for ASBT (48 kDa), t-ASBT (19 kDa) and β-Actin (41 kDa) and the bands were then visualized using enhanced chemiluminescence techniques. Densitometric values shown here are expressed as mean ± SE (^aP < 0.05) and represent 3 feeding studies for ASBT protein analyses of the TCA and CY groups. Similarly, 3 feeding studies were per-formed to reflect the data obtained on t-ASBT protein follow-ing CY feeding, but only 2 feeding studies were done for t-ASBT protein analysis of the TCA group. Ten rats per group were analyzed in each of these feeding studies, thus a total of 30 rats per feeding study were used in all of the above groups, whereas 20 rats were incorporated into the analysis of t-ASBT in the TCA group.

Figure 3 Q-RPA data demonstrating upregulation of ASBT and t-ASBT message following TCA feeding and downregulation of their message following CY feeding in ileum. Bar graphs demonstrating ASBT and t-ASBT mRNAs, in which 40 μg total cellular RNA isolated from cholangiocytes obtained from rats fed regular chow (C), 1% TCA or 5% CY incorporated diets were used. Densitometric values demonstrated here are expressed as mean ± SE and represent n = 3 feeding studies in which 30 rats in total were analyzed for each group (^aP < 0.05).

Figure 4 Effect of TCA and CY feeding on the amount of ASBT and t-ASBT protein in ileum. Bar graphs showing ratios of ASBT/β-actin and t-ASBT/β-Actin in PNS of ileal scrapings obtained from rats fed C, TCA and CY diets. Forty and 80 μg of protein were subjected to SDS-PAGE and immunoblotted to visualize ASBT and t-ASBT, respectively. Data shown here are representative of n = 3 feeding studies were analyzed per group and expressed as mean ± SE (^aP < 0.05). For the analysis of ASBT and t-ASBT in the TCA treated groups, 7 and 3 rats in total were used, respectively. Whereas, the number of animals ana-lyzed in the CY groups totaled 10 and 3 for ASBT and t-ASBT, respectively. Hence, the number of control rats was 17 for ASBT and 6 for t-ASBT in total.

Figure 5 Effect of TCA and CY feeding on taurocholate uptake by ASBT in rat IBDUs. Bar graphs showing 2.7-fold decrease and 1.7-fold increase in taurocholate uptake in TCA and CY fed rats, respectively, compared to controls. Data shown here, and expressed as mean ± SE, were obtained from n = 3 feeding stud-ies in which 11 control, 4 TCA and 5 CY IBDUs were analyzed (^aP < 0.05).