TBM-54 is an epithelial cell line derived in 1977 from the urinary bladder of a tropical toad collected in the Dominican Republic. The cells resemble the granular cell type of the urinary bladder. They have dense granules near the apical surface characteristic of the granular cell type found in the intact bladder. These cells form an epithelium with typical tight junctions and gap junctions and they form multilayers with one layer of undifferentiated cells interposed between the apical layer and the supporting structure. They exhibit hormone sensitive transepithelial electrical resistance, actively transport sodium and are subject to hormonal control in culture. Development of transepithelial electrical resistance (R) and transport rate (Isc) are dependent on time and the density of cells seeded, but steady state Isc and R is characteristic of the cell line and independent of seeding density. TBM-54 cells do not respond to vasopressin. Analogues of cAMP increase sodium transport and urea permeability but do not effect water permeability. Aldosterone increases sodium transport in a manner similar to that observed in intact bladder. TBM-54 cells exhibit an excellent response to mineralocortioids in serum free medium. |
