Swelling-activated, cystic fibrosis transmembrane conductance regulator-augmented ATP release and Cl- conductances in murine C127 cells

J Physiol. 2000 Feb 15;523 Pt 1(Pt 1):1-11. doi: 10.1111/j.1469-7793.2000.t01-6-00001.x.

Abstract

1. A hypotonic challenge, but not cAMP stimulation, was found to induce release of ATP measured by the luciferin-luciferase assay from both the murine mammary carcinoma cell line C127i and C127 cells stably transfected with the cDNA for human cystic fibrosis transmembrane conductance regulator (CFTR) protein (C127/CFTR). CFTR expression augmented swelling-induced ATP release by 10-20 times under hypotonic conditions (< or = 80 % osmolality). 2. Glibenclamide failed to suppress swelling-induced ATP release from C127/CFTR cells. In contrast, whole-cell patch-clamp recordings showed that both the cAMP-activated ohmic Cl- currents and volume-sensitive outwardly rectifying (VSOR) Cl- currents were prominently suppressed by glibenclamide. 3. Gd3+ markedly blocked swelling-induced ATP release but failed to suppress both cAMP- and swelling-activated Cl- currents in the CFTR-expressing cells. Even after pretreatment and during treatment with Gd3+, VSOR Cl- currents were activated normally. 4. The continuous presence of an ATP-hydrolysing enzyme, apyrase, in the bathing solution did not prevent activation of VSOR Cl- currents in C127/CFTR cells. 5. The rate of regulatory volume decrease (RVD) in C127/CFTR cells was much faster than that in C127i cells. When apyrase was added to the bathing solution, the RVD rate was retarded in C127/CFTR cells. 6. On balance, the following conclusions can be deduced. First, swelling-induced ATP release is augmented by expression of CFTR but is not mediated by the CFTR Cl- channel. Second, swelling-induced ATP release is not mediated by the VSOR Cl- channel. Third, the released ATP facilitated the RVD process but is not involved in the activation of VSOR Cl- channels in C127/CFTR cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism*
  • Animals
  • Apyrase / pharmacology
  • Chlorides / physiology*
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism
  • Cystic Fibrosis Transmembrane Conductance Regulator / physiology*
  • Electric Conductivity
  • Gadolinium / pharmacology
  • Glyburide / pharmacology
  • Humans
  • Mice
  • Tumor Cells, Cultured / drug effects
  • Tumor Cells, Cultured / metabolism
  • Tumor Cells, Cultured / pathology

Substances

  • CFTR protein, human
  • Chlorides
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • Adenosine Triphosphate
  • Gadolinium
  • Apyrase
  • Glyburide