Functional heterogeneity of cholangiocytes.

The objective of this article is to summarize the findings related to the notion that cholangiocytes, within small and large intrahepatic ducts, are heterogeneous regarding (1) morphology; (2) secretion in response to hormones and peptides and to bile acids; and (3) proliferation in response to injury or toxins, including bile duct ligation (BDL), acute carbon tetrachloride (CCl 4 ) administration, chronic feeding of bile salts (i.e., taurocholate [TC] or taurolithocholate [TLC]) or alpha-naphthylisothiocyanate (ANIT). After an overview of the morphology of the biliary epithelium, we provide a summary of cholangiocyte function, the in vivo models, and the in vitro experimental tools (i.e., small and large cholangiocytes or small and large intrahepatic bile duct units [IBDU]), which allowed us to demonstrate cholangiocyte heterogeneity. After a discussion on the receptors, transporters, and channels that are heterogeneously expressed by cholangiocytes, we discuss the different-sized ducts that differentially respond to injury and toxins. Finally, we review the human diseases that selectively target specific-sized ducts.