International Journal of Oral Biology

The Korean Academy of Oral Biology (대한구강생물학회)
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A role of Sodium Bicarbonate Cotransporter(NBC) in $HCO_3^-$ Formation in Human Salivary Gland Acinar Cells

  • Jin, Mee-Hyun (Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute,) ;
  • Koo, Na-Youn (Department of Physiology, School of Dentistry, Seoul National University) ;
  • Jin, Mei-Hong (Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute,) ;
  • Hwang, Sung-Min (Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute,) ;
  • Park, Kyung-Pyo (Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute,)
  • Published : 2008.12.31
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Abstract

The sodium bicarbonate cotransporter (NBC) protein is functionally expressed in salivary glands. In this experiment, we examined the role of NBC in $HCO_3^-$ formation in human parotid gland acinar cells. Intracellular pH (pHi) was measured in 2'-7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF)-loaded cells. Acetazolamide (0.1 mM) and 4,4'-diisothio cyanatostilbene-2,2'-disulphonic acid (DIDS, 0.5 mM) were used as specific inhibitors of carbonic anhydrase and NBC, respectively. The degree of inhibition was assessed by measuring the pHi recovery rate (${\Delta}pHi$/min) after cell acidification using an ammonium prepulse technique. In control experiments, ${\Delta}pHi$/min was $1.40{\pm}0.06$. Treatment of cells with 0.5 mM DIDS or 0.1 mM acetazolamide significantly reduced ${\Delta}pHi$/min to $1.14{\pm}0.14$ and $0.74{\pm}0.15$, respectively. Simultaneous application of DIDS and acetazolamide further reduced ${\Delta}pHi$/min to $0.47{\pm}0.10$. Therefore, DIDS and acetazolamide reduced ${\Delta}pHi$/min by 19% and 47%, respectively, while simultaneous application of both DIDS and acetazolamide caused a reduction in ${\Delta}pHi$/min of 67%. These results suggest that in addition to carbonic anhydrase, NBC also partially contributes to $HCO_3^-$ formation in human parotid gland acinar cells.

Keywords

References

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