ABSTRACT
Observations from a variety of model systems suggest that ductular bile formation
is mediated in large part by transepithelial transport of Cl- ions and have identified Cl- channels in the apical membrane as important targets for hormones and other factors
that modulate bile volume and composition through effects on duct cells. Signaling
through secretin receptors that stimulate adenylyl cyclase and activate the cystic
fibrosis transmembrane regulator (CFTR) Cl- channels represents a prototype for cholangiocyte secretion. However, recent observations
indicate that cholangiocytes also express a variety of receptors that modulate secretory
responses in the absence of effects on cyclic adenosine monophosphate (cAMP), and
Cl- channels unrelated to CFTR have been identified. Moreover, rapid exocytosis of subapical
vesicles is coupled closely to different Cl- secretory responses. These observations suggest that the protein composition of the
apical domain is regulated by selective exocytosis and endocytosis of channel-containing
vesicles, leading to rapid modulation of the transport capacity of individual cells
in response to changing physiologic demands.
KEYWORDS
Cholangiocyte - purinergic receptor - FM1-43
