Expansion of the bile acid pool changes the biliary transport characteristics of centrizonal hepatocytes

We investigated whether acinar differences in taurocholate transport are responsible for the increased maximal secretory rate observed after expansion of the bile acid pool. The bile acid pool was expanded by cholate feeding for four days. Periportal and centrizonal hepatocytes were then probed by ante- and retrograde liver perfusion, respectively. In control animals, secretory rate constant (alpha 1) averaged 0.439 +/- 0.123 and 0.104 +/- 0.035 min-1 during ante- and retrograde perfusion, respectively, in the absence of exogenous taurocholate. These values did not significantly change when taurocholate was infused. In cholate-fed animals, alpha 1 was comparable during antegrade perfusion but was significantly reduced (0.038 +/- 0.035, p less than 0.05) during retrograde perfusion in the absence of exogenous taurocholate, presumably owing to induction of cytosolic bile acid binding proteins. During loading with exogenous taurocholate, by contrast, alpha 1 was significantly accelerated (0.252 +/- 0.026; p less than 0.01) in centrizonal hepatocytes from bile-acid fed rats. Expansion of the bile acid pool is able to change the bile salt secretory characteristics of centrizonal hepatocytes toward those of periportal ones.