The Journal of Membrane Biology

, Volume 245, Issue 2, pp 107–115 | Cite as

Volume-Activated Chloride Currents in Fetal Human Nasopharyngeal Epithelial Cells

Article

Abstract

Volume-activated chloride channels have been studied by us extensively in human nasopharyngeal carcinoma cells. However, the chloride channels in the counterpart of the carcinoma cells have not been investigated. In this study, volume-activated chloride currents (Icl,vol) were characterized in normal fetal human nasopharyngeal epithelial cells using the whole-cell patch-clamp technique. Under isotonic conditions, nasopharyngeal epithelial cells displayed only a weak background current. Exposure to 47% hypotonic solution activated a volume-sensitive current. The reversal potential of the current was close to the calculated equilibrium potential for Cl. The peak values of the hypotonicity-activated current at +80 mV ranged from 0.82 to 2.71 nA in 23 cells. Further analysis indicated that the density of the hypotonicity-activated current in most cells (18/23) was smaller than 60 pA/pF. Only five cells presented a current larger than 60 pA/pF. The hypotonicity-activated current was independent of the exogenous ATP. Chloride channel inhibitors ATP, tamoxifen and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), inhibited the current dramatically. The anion permeability of the hypotonicity-activated chloride channels was I > Br > Cl > gluconate. Unexpectedly, in isotonic conditions, ATP (10 mM) activated an inward-rectified current, which had not been observed in the nasopharyngeal carcinoma cells. These results suggest that, under hypotonic challenges, fetal human nasopharyngeal epithelial cells can produce Icl,vol, which might be involved in cell volume regulation.

Keywords

Patch-clamp technique Regulation of ion transport by cell volume Ion channel/epithelial cell Epithelial chloride transport 

Notes

Acknowledgments

This work was supported by the National Natural Science Foundation of China (30771106, 30870567, 30871267, 90913020 and U0932004) and the Science & Technology Innovation Fund of Guangdong Medical College (STIF201102).

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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  1. 1.Institute of Aging Research, Key Laboratory for Medical Molecular Diagnostics of Guangdong ProvinceGuangdong Medical CollegeDongguanChina
  2. 2.Department of Pharmacology, Medical CollegeJinan UniversityGuangzhouChina
  3. 3.Department of PhysiologyGuangdong Medical CollegeZhanjiangChina
  4. 4.Department of Biology, Guangdong Key Laboratory for Bioactive Drugs ResearchGuangdong Pharmaceutical UniversityGuangzhouChina
  5. 5.Department of Physiology, Medical CollegeJinan UniversityGuangzhouChina

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