Inhibition of the endogenous volume-regulated anion channel (VRAC) in HEK293 cells by acidic di-aryl-ureas

J Membr Biol. 2003 Nov 15;196(2):83-94. doi: 10.1007/s00232-003-0627-x.

Abstract

The endogenous volume-regulated anion channel (VRAC) from HEK293 cells was pharmacologically characterized using the whole-cell patch-clamp technique. Under isotonic conditions a small (1.3 nS), Ca(2+)-independent Cl conductance was measured. However, swelling at 75% tonicity activated a VRAC identified as an outward-rectifying anion current ( P(l) > P(Cl) > P(gluconate)), which was ATP-dependent and showed inactivation at positive potentials. Activation of this current followed a sigmoid time course, reaching a plateau conductance of 42.6 nS after 12-15 min ( t(1/2) = 7 min). The pharmacology of this VRAC was investigated using standard Cl(-)-channel blockers (NPPB, DIDS, and tamoxifen) as well as a new group (acidic di-aryl ureas) of Cl(-)-channel blockers (NS1652, NS3623, NS3749, and NS3728). The acidic di-aryl ureas were originally synthezised for inhibition of the human erythrocyte Cl(-) conductance in vivo. NS3728 was the most potent VRAC blocker in this series ( IC(50) = 0.40 micro M) and even more potent than tamoxifen (2.2 micro M). NS3728 accelerated channel inactivation at positive potentials. These results show that acidic di-aryl ureas constitute a promising starting point for the synthesis of potent inhibitors of VRAC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzoates / pharmacology
  • Calcium Channel Blockers / pharmacology*
  • Cell Line
  • Cells, Cultured
  • Chloride Channels / antagonists & inhibitors*
  • Chloride Channels / physiology*
  • Dose-Response Relationship, Drug
  • Erythrocytes / drug effects
  • Erythrocytes / physiology
  • Humans
  • Hydrogen-Ion Concentration
  • Ion Channel Gating / drug effects
  • Ion Channel Gating / physiology*
  • Kidney / drug effects
  • Kidney / embryology
  • Kidney / physiology*
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology*
  • Phenylurea Compounds / pharmacology*
  • Tetrazoles / pharmacology
  • Urea / pharmacology

Substances

  • Benzoates
  • Calcium Channel Blockers
  • Chloride Channels
  • NS 3623
  • Phenylurea Compounds
  • Tetrazoles
  • Urea
  • NS 1652