s / Pancreatology 15 (2015) S1eS141 S47 Results: HAT-7 cells formed epithelial layers with measureable TER on Transwell permeable supports, and expressed key tight junction proteins claudin-1, -4 and -8. Transport proteins described in maturation ameloblasts were also present in HAT-7 cells. By microfluorometry we found that the cells were polarized with a high apical membrane CO2 permeability and vigorous basolateral HCO3 uptake which was sensitive to Naþ withdrawal, to the carbonic anhydrase inhibitor acetazolamide and to H2DIDS inhibition. Measurements of transepithelial HCO3 transport showed a marked increase in response to Ca2þand cAMP-mobilizing stimuli. Taken together, these studies provide evidence for a regulated, vectorial, basolateral to apical bicarbonate transport in polarized HAT-7 cells. Conclusion: We propose that the HAT-7 cell line is a useful functional model for studying electrolyte transport of ameloblasts. Supported by NIH-NIDCR (5R01DE013508subaward:7743sc), TAMOP4.2.1/B-09/1/KMR-2010-0001, TAMOP-4.2.2/B-10/1-2010-0013.