Expression of a glutamate-activated chloride current in Xenopus oocytes injected with Caenorhabditis elegans RNA: evidence for modulation by avermectin

Brain Res Mol Brain Res. 1992 Oct;15(3-4):339-48. doi: 10.1016/0169-328x(92)90127-w.


Membrane currents were recorded from Xenopus laevis oocytes injected with C. elegans poly(A)+ RNA. In such oocytes glutamate activated an inward membrane current that desensitized in the continued presence of glutamate. Glutamate-receptor agonists quisqualate, kainate, and N-methyl-D-aspartate were inactive. The reversal potential of the glutamate-sensitive current was -22 mV, and exhibited a strong dependence on external chloride with a 48 mV change for a 10-fold change in chloride. The chloride channel blockers flufenamate and picrotoxin inhibited the glutamate-sensitive current. Ibotenate, a structural analog of glutamate, also activated a picrotoxin-sensitive chloride current. Ibotenate was inactive when current was partially desensitized with glutamate, and the responses to low concentrations of glutamate and ibotenate were additive. The anthelmintic/insecticide compound avermectin directly activated the glutamate-sensitive current. In addition, avermectin increased the response to submaximal concentrations of glutamate, shifted the glutamate concentration-response curve to lower concentrations, and slowed the desensitization of glutamate-sensitive current. We propose that the glutamate-sensitive chloride current and the avermectin-sensitive chloride current are mediated via the same channel.

MeSH terms

  • Animals
  • Anthelmintics / pharmacology
  • Caenorhabditis elegans / drug effects*
  • Caenorhabditis elegans / genetics
  • Cell Membrane Permeability / drug effects
  • Chloride Channels
  • Chlorides*
  • Glutamates / pharmacology*
  • Glutamic Acid
  • Ibotenic Acid / pharmacology
  • Ion Channel Gating / drug effects
  • Ivermectin / analogs & derivatives
  • Ivermectin / pharmacology
  • Membrane Proteins / drug effects*
  • Microinjections
  • Oocytes / drug effects*
  • Poly A / genetics*
  • RNA / genetics*
  • Xenopus laevis


  • Anthelmintics
  • Chloride Channels
  • Chlorides
  • Glutamates
  • Membrane Proteins
  • Poly A
  • Ibotenic Acid
  • Glutamic Acid
  • RNA
  • Ivermectin
  • avermectin