Abstract
The effects of chlorisondamine on glutamate-activated channels are described. Chlorisondamine reduced the amplitude of intracellularly recorded excitatory junctional potentials and of responses to iontophoretically applied glutamate. Dose-response curves indicate a noncompetitive interaction. Extracellularly recorded synaptic currents were recorded while holding muscles at different membrane potentials. Chlorisondamine reduced the peak amplitude of synaptic currents and changed the time course of decay. Analysis of these results suggests that chlorisondamine blocks the glutamate-gated channel.
ACKNOWLEDGMENTS We thank Ciba-Geigy for the gift of chlorisondamine. Dr. Chris Miller very kindly allowed us to use his computer and wrote the programs we used for this analysis. We thank Dr. A. Auerbach for many helpful discussions, Mr. Michael White for reading the manuscript, Ms. Jill Suttles and Mr. Michael O’Neil for help with the figures, and Ms. Maureen Delaney for typing the manuscript.