The cultured human gastric cells HGT-1 express the principal transporters involved in acid secretion

I-IGT-I is a human cell line sharing a number of physiological features wit h gastric parietal cells. HGT-1 cell monolayers were able to secrete H+ whe n stimulated with histamine (calculated external pH variation, Delta pH(e) 0.46+/-0.05) as assessed using the impermeant, pH-sensitive: fluorescence d ye 8-hydroxypyrene-1,3,6-trisulphonic acid, trisodium salt (HPTS). Treatmen t with 100 muM omeprazole inhibited the histamine-induced apical acidificat ion by about 60%. Intracellular pH (pH(i)) measurements using the fluoresce nt pH-sensitive dye 2',7'-bis-carboxyethyl-5(6)-carboxyfluorescein (BCECF) demonstrated the expression of a functional, omeprazole-sensitive H+/K+-pum p. A monoclonal antibody directed against the alpha subunit of the H+/K+-AT Pase immunoprecipitated a 95-kDa protein From HGT-1 cells and human stomach which corresponds to the expected molecular size of the native protein. HG T-1 cells were also positive for the anion exchanger AE2 that is expressed in gastric parietal cells. In addition, we identified a histamine- and pH(i )-sensitive Na+/H+ exchanger in HCT-I cells, which might correspond to the functional expression of the NHE4 isoform that has been detected in gastric epithelial cells as well as in primary cultured parietal cells. HGT-1 cell s therefore display the principal features of parietal cells and might repr esent an interesting cell culture model for studying the regulatory mechani sms involved in acid secretion.