Intracellular pH regulatory mechanism in a human renal proximal cell line (HKC-8): Evidence for Na+/H+ exchanger, Cl-/HCO3- exchanger and Na+-HCO3- cotransporter

Chiaki Hara, Hiroaki Satoh, Tomohiko Usui, Motoei Kunimi, Eisei Noiri, Kazuhisa Tsukamoto, Shigeo Taniguchi, Shu Uwatoko, Astuo Goto, Lorraine C. Racusen, Jun Inatomi, Hitoshi Endou, Toshiro Fujita, George Seki

Research output: Contribution to journalArticlepeer-review


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 (pH(i)) 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 pH(i) 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 pH(i) 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.

Original languageEnglish (US)
Pages (from-to)713-720
Number of pages8
JournalPflugers Archiv European Journal of Physiology
Issue number5
StatePublished - Jan 1 2000


  • BC-1
  • Cell pH
  • Cl/HCO exchanger
  • HKC-8
  • Na/H exchanger
  • Proximal tubular cells

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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