Sustained calcium entry through P2X nucleotide receptor channels in human airway epithelial cells.

Academic Article

Abstract

  • Purinergic receptor stimulation has potential therapeutic effects for cystic fibrosis (CF). Thus, we explored roles for P2Y and P2X receptors in stably increasing [Ca(2+)](i) in human CF (IB3-1) and non-CF (16HBE14o(-)) airway epithelial cells. Cytosolic Ca(2+) was measured by fluorospectrometry using the fluorescent dye Fura-2/AM. Expression of P2X receptor (P2XR) subtypes was assessed by immunoblotting and biotinylation. In IB3-1 cells, ATP and other P2Y agonists caused only a transient increase in [Ca(2+)](i) derived from intracellular stores in a Na(+)-rich environment. In contrast, ATP induced an increase in [Ca(2+)](i) that had transient and sustained components in a Na(+)-free medium; the sustained plateau was potentiated by zinc or increasing extracellular pH. Benzoyl-benzoyl-ATP, a P2XR-selective agonist, increased [Ca(2+)](i) only in Na(+)-free medium, suggesting competition between Na(+) and Ca(2+) through P2XRs. Biochemical evidence showed that the P2X(4) receptor is the major subtype shared by these airway epithelial cells. A role for store-operated Ca(2+) channels, voltage-dependent Ca(2+) channels, or Na(+)/Ca(2+) exchanger in the ATP-induced sustained Ca(2+) signal was ruled out. In conclusion, these data show that epithelial P2X(4) receptors serve as ATP-gated calcium entry channels that induce a sustained increase in [Ca(2+)](i). In airway epithelia, a P2XR-mediated Ca(2+) signal may have therapeutic benefit for CF.
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    Published In

    Keywords

  • Adenosine Diphosphate, Adenosine Triphosphate, Calcium, Calcium Channels, Cell Line, Cytosol, Fluorescent Dyes, Humans, Kinetics, Microscopy, Fluorescence, Receptors, Purinergic P2, Receptors, Purinergic P2X, Respiratory Mucosa, Uridine Triphosphate
  • Digital Object Identifier (doi)

    Pubmed Id

  • 23304605
  • Author List

  • Zsembery A; Boyce AT; Liang L; Peti-Peterdi J; Bell PD; Schwiebert EM
  • Start Page

  • 13398
  • End Page

  • 13408
  • Volume

  • 278
  • Issue

  • 15