Role of calcium in volume-activated chloride currents in a mouse cholangiocyte cell line

Biyi Chen, Grant Nicol, Won Kyoo Cho

Research output: Contribution to journalReview articlepeer-review

15 Scopus citations

Abstract

Volume-activated Cl- channels (VACCs) play vital roles in many cells including cholangiocytes. Previously, we characterized the VACCs in mouse cholangiocytes. Since calcium plays an important role in VACC regulation in many cells, we have studied the effect of calcium modulation on the regulatory volume decrease (RVD) and VACC currents in mouse bile duct cells (MBDCs). Cell volume measurements were assessed by a Coulter counter with cell sizer, and conventional whole-cell patch-clamp techniques were used to study the role of calcium on RVD and VACC currents. Cell volume study indicated that MBDCs exhibited RVD, which was inhibited by 5-nitro-2′-(3-phenylpropylamino)- benzoate (NPPB), 4,4′-diisothiocyanostilbene-2,2′-disulfonate (DIDS) and 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetra-acetoxymethyl ester (BAPTA-AM) but not by removal of extracellular calcium. During hypotonic challenge, MBDCs exhibited an outwardly rectified current, which was significantly inhibited by administration of classical chloride channel inhibitors such as NPPB and tamoxifen. Chelation of the intracellular calcium with BAPTA-AM or removal of extracellular calcium and calcium channel blocker had no significant effect on VACC currents during hypotonic challenge. In addition to VACC, MBDC had a calcium-activated chloride channel, which was inhibited by NPPB. The present study is the first to systemically study the role of calcium on the VACC and RVD in mouse cholangiocytes and demonstrates that a certain level of intracellular calcium is necessary for RVD but the activation of VACC during RVD does not require calcium. These findings suggest that calcium does not have a direct regulatory role on VACC but has a permissive role on RVD in cholangiocytes.

Original languageEnglish (US)
Pages (from-to)1-13
Number of pages13
JournalJournal of Membrane Biology
Volume215
Issue number1
DOIs
StatePublished - Jan 1 2007

Keywords

  • Bile duct cell
  • Calcium
  • Cell volume
  • Ion channel
  • Mouse cholangiocyte
  • Patch clamping
  • Regulatory volume decrease
  • Volume-activated chloride channel

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

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