title: The actions of 'selective' excitatory amino acid antagonists on the crustacean neuromuscular junction.
abstract: Intracellular recordings of neurally evoked excitatory junction potentials were made from the hermit crab neuromuscular junction and the effects of a series of putative antagonists, including the phosphonic amino acids, were examined for their effectiveness. The most potent antagonists were (+/-)2-amino-5-phosphonohexanoic acid and (+/-) 2-amino-5-phosphonovaleric acid while glutamate diethyl ester, DL-alpha-aminoadipate, 2-amino-7-phosphonoheptanoic acid and gamma-D-glutamylglycine were less effective. None of the compounds produced a change in membrane input resistance, but pyridine-2,5-dicarboxylic acid depolarized the muscle membrane and this probably accounted for its apparent antagonist properties. All the compounds readily and reversibly, but not competitively, antagonized the ionophoretic L-glutamate-induced depolarization. Since none of the compounds was capable of producing complete antagonism it is concluded that a more potent and competitive antagonist is required.
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives; D015074:2-Aminoadipic Acid / Q000494:pharmacology; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D033381:Anomura; D004151:Dipeptides / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D009469:Neuromuscular Junction / Q000187:drug effects*; D009646:Norleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D004151:Dipeptides; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates; D011725:Pyridines; C011829:glutamic acid diethyl ester; C028929:gamma-glutamylglycine; D015074:2-Aminoadipic Acid; D018698:Glutamic Acid; C043093:2,5-Pyridinedicarboxylic acid; D015763:2-Amino-5-phosphonovalerate; C043094:2-amino-6-phosphonohexanoic acid; D009646:Norleucine; D014633:Valine; C031231:2-amino-7-phosphonoheptanoic acid