We have developed a cell culture of guinea pig gallbladder epithelial cells with which to study ion transport. When grown on permeable supports, the cultured epithelia developed a transepithelial resistance (R t ) of ∼500 Ω·cm 2 . The epithelial cell origin of the cell culture was further confirmed by immunocytochemical localization of cytokeratin. Ionomycin and forskolin increased transepithelial voltage and short-circuit current (I sc ) and decreased R t . The response to ionomycin was transient, whereas that to forskolin was sustained. Both were attenuated by replacement of Cl − and/or . Mucosal addition of the anion transport inhibitors DIDS or diphenylamine-2-carboxylic acid (DPC) blocked the response to ionomycin. The response to forskolin was blocked by DPC but not by DIDS. Ionomycin, but not forskolin, increased intracellular Ca 2+ concentration in fura 2-loaded cells. PGE 2 , histamine, vasoactive intestinal polypeptide, and secretin elicited a sustained increase in I sc . Responses to ATP and CCK were transient. Thus cultured guinea pig gallbladder epithelia display the range of responses observed in the native tissue and are an appropriate model for studies of ion transport in gallbladder and intestinal epithelia. Keywords cultured cells; histamine; ATP; vasoactive intestinal polypeptide; prostaglandin E 2 ; secretin; cholecystokinin; anion secretion; diphenylamine-2-carboxylic acid; 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid; ionomycin; intracellular Ca 2+ ; forskolin; cAMP Cell Culture Systems Provide a homogeneous population of cells that can be grown and studied under defined conditions and manipulated to express foreign proteins. As such, the availability of tissue culture cells has enhanced the ability of investigators to study a wide range of biological and biochemical processes. In gastrointestinal epithelia, cell cultures have been used to study ion transport processes and their regulation by second-messenger pathways. Many of the cell culture systems widely used to study intestinal ion transport, such as T84 (15), 21), and , are derived from colonic carcinomas.Copyright © 2000 the American Physiological Society Address for reprint requests and other correspondence: P. J. Gunter-Smith, Dept. of Biology, Spelman College, Atlanta, GA 30314 (pgunter@spelman.edu). NIH Public Access Author ManuscriptAm J Physiol Gastrointest Liver Physiol. Author manuscript; available in PMC 2015 January 22. NIH-PA Author ManuscriptAlthough these cells display many of the transport characteristics of the normal colonic tissue type from which they were derived, some investigators have suggested caution in their use because of their tumor origin (17).Obtaining established cell lines or primary cultures of cells derived from the small intestine that display the transport characteristics of more proximal regions of the intestine has been more problematic. For example, the established non-tumor-derived cell line IEC-6 forms a confluent monolayer but maintains many characteristics of poorly differentiated...