Inhibitory actions of vecuronium bromide on acetylcholine and glutamate responses at the frog and crayfish neuromuscular junction.
Effects of vecuronium bromide, an analog of pancuronium, on the cholinergic and glutamatergic neuromuscular junction were investigated. Vecuronium depressed the postsynaptic response of the frog end-plate at lower concentrations than 10(-6) g/ml without affecting the presynaptic events. Vecuronium decreased the amplitude of the double ACh potential, but the second potential was more markedly reduced than the first. In analogy with d-tubocurarine, this suggests that vecuronium may act in part as an open channel blocker at the frog end-plate. Vecuronium depressed both the glutamate response and the excitatory junctional potential at the crayfish neuromuscular junction, although high concentrations were required. The drug increased the decay rate of extracellularly recorded excitatory junctional potentials at the crayfish neuromuscular junction. The reduction of the crayfish synaptic response caused by vecuronium can be explained by the open channel blocking action at this junctional site. The problem that cholinergic antagonists possess a property of channel blocking at the other transmitter system was discussed.
D000109:Acetylcholine / Q000037:antagonists & inhibitors*; D000818:Animals; D003400:Astacoidea; D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid; D066298:In Vitro Techniques; D009045:Motor Endplate / Q000187:drug effects; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology*; D009469:Neuromuscular Junction / Q000187:drug effects*; D010197:Pancuronium / Q000031:analogs & derivatives* / Q000494:pharmacology; D011892:Rana catesbeiana; D013569:Synapses / Q000187:drug effects; D013997:Time Factors; D014673:Vecuronium Bromide
D018691:Excitatory Amino Acid Antagonists; D009466:Neuromuscular Blocking Agents; D018698:Glutamic Acid; D014673:Vecuronium Bromide; D010197:Pancuronium; D000109:Acetylcholine