Skip to main content
Article thumbnail
Location of Repository

The actions of chloride channel blockers, barbiturates and a benzodiazepine on Caenorhabditis elegans glutamate- and ivermectin-gated chloride channel subunits expressed in Xenopus oocytes

By Elizabeth Bush, Richard Foreman, Robert J. Walker and Lindy Holden-Dye


The pharmacology of Caenorhabditis elegans glutamate-gated chloride (GluCl) channels was determined by making intracellular voltage-clamp recordings from Xenopus oocytes expressing GluCl subunits. As previously reported (Cully et al. 1994), GluClalpha1beta responded to glutamate (in a picrotoxin sensitive manner) and ivermectin, while GluClbeta responded only to glutamate and GluClalpha1 only to ivermectin. This assay was used to further investigate the action of chloride channel compounds. The arylaminobenzoate, NPPB, reduced the action of glutamate on the heteromeric GluClalpha1beta channel (IC(50) 6.03 +/- 0.81 microM). The disulphonate stilbene, DNDS, blocked the effect of both glutamate and ivermectin on GluClalpha1beta channels, the action of glutamate on GluClbeta subunits, and the effect of ivermectin on GluClalpha1 subunits (IC(50)s 1.58-3.83 microM). Surprisingly, amobarbital and pentobarbital, otherwise known as positive allosteric modulators of ligand-gated chloride channels, acted as antagonists. Both compounds reduced the action of glutamate on the GluClalpha1beta heteromer (IC(50)s of 2.04 +/- 0.5 and 17.56 +/- 2.16 microM, respectively). Pentobarbital reduced the action of glutamate on the GluClbeta homomeric subunit with an IC(50) of 0.59 +/- 0.09 microM, while reducing the responses to ivermectin on both GluClalpha1beta and GluClalpha1 with IC(50)s of 8.7 +/- 0.5 and 12.9 +/- 2.5 microM, respectively. For all the antagonists, the mechanism is apparently non-competitive. The benzodiazepine, flurazepam had no apparent effect on these glutamate- and ivermectin-gated chloride channel subunits. Thus, arylaminobenzoates, disulphonate stilbenes, and barbiturates are non-competitive antagonists of C. elegans GluCl channels.<br/><br/

Year: 2009
OAI identifier:
Provided by: e-Prints Soton

Suggested articles


  1. (1997). avr-15 encodes a chloride channel subunit that mediates inhibitory glutamatergic neurotransmission and ivermectin sensitivity in Caenorhabditis elegans. doi
  2. (2005). Critical amino acid residues involved in the electrogenic sodium-bicarbonate cotransporter kNBC1-mediated transport. J Physiol 565:717–730 Betz H doi
  3. (1995). Evolutionary history of the ligand-gated ion-channel superfamily of receptors. Trends Neurosci 18:121– doi
  4. (1982). The actions of L-glutamate and putative glutamate agonists on the central neurones of Limulus polyphemus. Comp Biochem Physiol 73C:167–175

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.