title: The excitatory actions of kainic acid and some derivatives at the crab neuromuscular junction.
abstract: The actions of kainic acid and its derivatives including the new tricarboxylic kainic acid were tested on the Hermit crab neuromuscular junction. Kainic acid had a direct excitatory effect producing a depolarization. Although not so potent, alpha-ketokainic acid and tricarboxylic kainic acid mimicked this effect whilst dihydrokainic acid did not. The slopes of the dose-response curves for these kainic acid analogues differed from that of L-glutamate. A Hill coefficient approximating one was obtained for kainic acid compared to a value of three for L-glutamate. Threshold concentrations of l-glutamate and kainic acid but not alpha-ketokainic acid and tricarboxylic kainic acid potentiated the neurally evoked excitatory junction potentials and the ionophoretic L-glutamate potential. The results indicate a possible interaction of the kainic acid derivatives with a heterogeneous receptor population and provide a comparison with other invertebrate and vertebrate systems.
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D033381:Anomura / Q000502:physiology*; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*; D008968:Molecular Conformation; D009469:Neuromuscular Junction / Q000187:drug effects*; D011759:Pyrrolidines / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D005971:Glutamates; D011759:Pyrrolidines; D018698:Glutamic Acid; D007608:Kainic Acid