OBJECTIVES: The human pancreatic duct cell line, HPAF, has been shown previously to secrete Cl(-) in response to Ca(2+)-mobilizing stimuli. Our aim was to assess the capacity of HPAF cells to transport and secrete HCO3(-). METHODS: HPAF cells were grown as confluent monolayers on permeable supports. Short-circuit current was measured by voltage clamp. Intracellular pH (pHi) was measured by microfluorometry in cells loaded with 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). RESULTS: In HCO3(-)-free solutions, ATP-evoked changes in short-circuit current were inhibited by bumetanide, and the recovery of pHi from acid loading was abolished by 5-(N-ethyl-N-isopropyl)-amiloride (EIPA). In the presence of HCO3(-), ATP-evoked secretion was no longer inhibited by bumetanide, and there was a strong EIPA-insensitive recovery from acid loading, which was inhibited by 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonate (H2DIDS). ATP, but not forskolin, stimulated HCO3(-) efflux from the cells. CONCLUSIONS: In the absence of HCO3(-), ATP-evoked Cl(-) secretion is driven by a basolateral Na(+)-K(+)-2Cl(-) cotransporter, and pH(i) is regulated by apical and basolateral Na(+)/H(+) exchangers. In the presence of HCO3(-), ATP-evoked secretion is sustained in the absence of Na(+)-K(+)-2Cl(-) cotransporter activity and is probably driven by basolateral Na(+)-HCO3(-) cotransport.
OBJECTIVES: The humanpancreatic duct cell line, HPAF, has been shown previously to secrete Cl(-) in response to Ca(2+)-mobilizing stimuli. Our aim was to assess the capacity of HPAF cells to transport and secrete HCO3(-). METHODS: HPAF cells were grown as confluent monolayers on permeable supports. Short-circuit current was measured by voltage clamp. Intracellular pH (pHi) was measured by microfluorometry in cells loaded with 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). RESULTS: In HCO3(-)-free solutions, ATP-evoked changes in short-circuit current were inhibited by bumetanide, and the recovery of pHi from acid loading was abolished by 5-(N-ethyl-N-isopropyl)-amiloride (EIPA). In the presence of HCO3(-), ATP-evoked secretion was no longer inhibited by bumetanide, and there was a strong EIPA-insensitive recovery from acid loading, which was inhibited by 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonate (H2DIDS). ATP, but not forskolin, stimulated HCO3(-) efflux from the cells. CONCLUSIONS: In the absence of HCO3(-), ATP-evoked Cl(-) secretion is driven by a basolateral Na(+)-K(+)-2Cl(-) cotransporter, and pH(i) is regulated by apical and basolateral Na(+)/H(+) exchangers. In the presence of HCO3(-), ATP-evoked secretion is sustained in the absence of Na(+)-K(+)-2Cl(-) cotransporter activity and is probably driven by basolateral Na(+)-HCO3(-) cotransport.
Authors: E Bori; J Guo; R Rácz; B Burghardt; A Földes; B Kerémi; H Harada; M C Steward; P Den Besten; A L J J Bronckers; G Varga Journal: J Dent Res Date: 2016-01-20 Impact factor: 6.116
Authors: Róbert Rácz; Anna Földes; Erzsébet Bori; Ákos Zsembery; Hidemitsu Harada; Martin C Steward; Pamela DenBesten; Antonius L J J Bronckers; Gábor Gerber; Gábor Varga Journal: Front Physiol Date: 2017-12-06 Impact factor: 4.566