Similarity of A(3)-adenosine and swelling-activated Cl(-) channels in nonpigmented ciliary epithelial cells

Am J Physiol Cell Physiol. 2000 Aug;279(2):C440-51. doi: 10.1152/ajpcell.2000.279.2.C440.


Chloride release from nonpigmented ciliary epithelial (NPE) cells is a final step in forming aqueous humor, and adenosine stimulates Cl(-) transport by these cells. Whole cell patch clamping of cultured human NPE cells indicated that the A(3)-selective agonist 1-deoxy-1-(6-[([3-iodophenyl]methyl)amino]-9H-purin-9-yl)-N-methyl-be ta-D-ribofuranuronamide (IB-MECA) stimulated currents (I(IB-MECA)) by approximately 90% at +80 mV. Partial replacement of external Cl(-) with aspartate reduced outward currents and shifted the reversal potential (V(rev)) from -23 +/- 2 mV to -0.0 +/- 0.7 mV. Nitrate substitution had little effect. Perfusion with the Cl(-) channel blockers 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and niflumic acid inhibited the currents. Partial Cl(-) replacement with aspartate and NO(3)(-), and perfusion with NPPB, had similar effects on the swelling-activated whole cell currents (I(Swell)). Partial cyclamate substitution for external Cl(-) inhibited inward and outward currents of both I(IB-MECA) and I(Swell). Both sets of currents also showed outward rectification and inactivation at large depolarizing potentials. The results are consistent with the concept that A(3)-subtype adenosine agonists and swelling activate a common population of Cl(-) channels.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine / analogs & derivatives
  • Adenosine / pharmacology
  • Cells, Cultured
  • Chloride Channels / drug effects
  • Chloride Channels / physiology*
  • Cilia / drug effects
  • Cilia / physiology*
  • Epithelial Cells / drug effects
  • Epithelial Cells / physiology*
  • Humans
  • Purinergic P1 Receptor Agonists
  • Receptor, Adenosine A3
  • Receptors, Purinergic P1 / physiology*


  • Chloride Channels
  • Purinergic P1 Receptor Agonists
  • Receptor, Adenosine A3
  • Receptors, Purinergic P1
  • N(6)-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine
  • Adenosine