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- Title
Intracellular pH regulatory mechanism in a human renal proximal cell line (HKC-8): evidence for Na<sup>+</sup>/H<sup>+</sup> exchanger, Cl<sup>–</sup>/HCO<sub>3</sub><sup>–</sup> exchanger and Na<sup>+</sup>-HCO<sub>3</sub><sup>–</sup> cotransporter
- Authors
Hara, Chiaki; Satoh, Hiroaki; Usui, Tomohiko; Kunimi, Motoei; Noiri, Eisei; Tsukamoto, Kazuhisa; Taniguchi, Shigeo; Uwatoko, Shu; Goto, Astuo; Racusen, Lorraine C.; Inatomi, Jun; Endou, Hitoshi; Fujita, Toshiro; Seki, George
- Abstract
In the present study we investigated whether an immortalized human renal proximal cell line, HKC-8, expresses a recently cloned Na+-HCO3– cotransporter (NBC-1) and, if so, which isoform (kNBC-1 from kidney or pNBC-1 from pancreas) is expressed in this cell line. Cell pH (pHi) measurements using a pH-sensitive fluorescence probe in the absence of HCO3–/CO2 revealed the presence of a Na+/H+ exchanger that required high concentrations of amiloride for full inhibition. In the presence of HCO3–/CO2 another pHi recovery process, dependent on Na+ but independent of Cl–, was identified. This process was electrogenic and was inhibited by 4,4′-diisothiocyanatodihydrostilbene-2,2′-disulphonic acid (DIDS), being consistent with the Na+-HCO3– cotransporter. In addition, the pHi responses to Cl– removal were compatible with the presence of a Na+-independent Cl–/HCO3– exchanger that was also inhibited by DIDS. Reverse transcriptase polymerase chain reaction (RT-PCR) using primers designed for specific and common regions detected mRNAs of both kNBC-1 and pNBC-1 and Western blot analysis confirmed the expression of NBC-1 protein. These results indicate that HKC-8 has transport activities similar to intact proximal tubules and also suggest that both kNBC-1 and pNBC-1 may contribute to the Na+-HCO3– cotransport activity in this cell line.
- Subjects
CELL lines; CELL culture; CELLULAR mechanics; POLYMERASE chain reaction; DIURETICS; AMILORIDE
- Publication
Pflügers Archiv: European Journal of Physiology, 2000, Vol 440, Issue 5, p713
- ISSN
0031-6768
- Publication type
Article
- DOI
10.1007/s004240000356