Article

The Journal of Membrane Biology

, Volume 245, Issue 2, pp 107-115

First online:

Volume-Activated Chloride Currents in Fetal Human Nasopharyngeal Epithelial Cells

  • Xuerong SunAffiliated withInstitute of Aging Research, Key Laboratory for Medical Molecular Diagnostics of Guangdong Province, Guangdong Medical CollegeDepartment of Physiology, Guangdong Medical College
  • , Lixin ChenAffiliated withDepartment of Pharmacology, Medical College, Jinan University Email author 
  • , Haibing LuoAffiliated withDepartment of Physiology, Guangdong Medical College
  • , Jianwen MaoAffiliated withDepartment of Biology, Guangdong Key Laboratory for Bioactive Drugs Research, Guangdong Pharmaceutical University
  • , Linyan ZhuAffiliated withDepartment of Pharmacology, Medical College, Jinan University
  • , Sihuai NieAffiliated withDepartment of Physiology, Guangdong Medical College
  • , Liwei WangAffiliated withDepartment of Physiology, Medical College, Jinan University Email author 

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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