These studies investigated the growth characteristics and functional properties of isolated canine pancreatic ductal epithelial cells. Cells were isolated from the accessory pancreatic duct and cultured by using three conditions: on vitrogen-coated petri dishes with fibroblast conditioned medium (nonpolarized); in vitrogen-coated Transwells above a fibroblast feeder layer (polarized); or as organotypic rafts above a fibroblast-embedded collagen layer (polarized). Growth characteristics, transepithelial resistances, and carbonic anhydrase and cyclic adenosine monophosphate (AMP) responses were evaluated. Under polarized conditions, the cells grew as monolayers with columnar epithelial characteristics. The monolayers developed high transepithelial resistance and became impervious to the passage of horseradish peroxidase. Epithelial growth factor (EGF) (2 ng/ml) stimulated ductal cell growth and accelerated the formation of a high-resistance monolayer. Forskolin (10 microM) rapidly decreased transepithelial resistance. Carbonic anhydrase activity, which was lower in nonpolarized compared with polarized conditions, was stimulated by carbachol (175 microM). Secretin, however, did not stimulate carbonic anhydrase activity in these cells. Although secretin stimulated adenylyl cyclase activity in early-passage cells, this response was lost in later-passage cells. Both vasoactive intestinal polypeptide (VIP; 1 microM) and forskolin (10 microM) consistently increased adenylyl cyclase activity. Isolated canine pancreatic ductal epithelial cells proliferate in vitro, develop high-resistance epithelial monolayers, and respond to stimuli that activate adenylyl cyclase. These cells should provide a useful model for regulatory studies of ductal cell functions.