title: Basolateral mechanisms of intracellular pH regulation in the colonic epithelial cell line HT29 clone 19A.
abstract: The intracellular pH (pHi) of the colonic tumour cell line HT29 cl.19A was studied by microspectrofluorometry using the pH-sensitive dye BCECF. Single cells within a confluent monolayer, grown in a polarized manner on permeable supports, were examined. An amiloride-sensitive Na+/H+ exchange and a stilbene-insensitive Cl-/HCO3- exchange mechanism have been identified in the basolateral membrane. Removal of Na+ from the basolateral solution caused a decrease of pHi by 0.50 +/- 0.09 unit (n = 4). Amiloride or Na(+)-free solution at the apical side had no effect on pHi. Cl- removal at the basolateral side led to an increase of pHi by 0.20 +/- 0.03 unit (n = 4) whereas apical removal had no influence on pHi. This effect was independent of Na+ and was insensitive to 0.2 mM 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulphonic acid. A basolateral Cl-/HCO3- exchanger is the most likely explanation for this observation. The Na+/H+ exchange mechanism in the basolateral membrane is an acid extruder, whereas the Cl-/HCO3- exchanger is an acid loader. Both of these mechanisms are important for the maintenance of intracellular pH in HT29 cl.19A cells.
authors.affiliation: Physiologisches Institut, Tierärztlichen Hochschule Hannover, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Busche
authors.forename: A
authors.initials: A
authors.lastname: Jeromin
authors.forename: W
authors.initials: W
authors.lastname: von Engelhardt
authors.forename: G
authors.initials: G
authors.lastname: Rechkemmer
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D002999:Clone Cells; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005452:Fluoresceins; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D012964:Sodium / Q000502:physiology; D013050:Spectrometry, Fluorescence; D014407:Tumor Cells, Cultured
chemical_list: D001639:Bicarbonates; D002712:Chlorides; D005452:Fluoresceins; C057433:2',7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein acetoxymethyl ester; D000584:Amiloride; D012964:Sodium