Electrophysiological investigation of GABA-mediated inhibition at the hermit crab neuromuscular junction

摘要: 1. The inhibitory neuromuscular junction of the abductor muscle large claw hermit crab (Eupagurus bernhardus) was investigated using electrophysiological intracellular techniques in order to elucidate further relative contributions pre- and post-synaptic mechanisms action GABA neural inhibition.2. electrical constants membrane, calculated equations for a ;short cable' model, were characteristic poorly developed excitability; specific membrane resistance usually 40 muF/cm(2).3. Stimulation excitatory axon at frequency 20 Hz evoked highly facilitating potentials (e.j.p.s); stimulation (60-220 Hz) during train elicited inhibition which manifest as an attenuation e.j.p.s.4. addition gamma-aminobutyric acid (GABA) bathing solution produced dose-dependent reduction e.j.p. amplitude resistance. effect concentrations (5 x 10(-5) 1 10(-4)M) caused 40-75% could largely be accounted by on conductance.5. Experiments with picrotoxin suggest that presynaptic have important role neurally inhibition.6. Picrotoxin (1-5 10(-5)M) effectively blocked actions this preparation, whereas bicuculline proved considerably less potent therefore useful physiological tool studying GABA-mediated crustacea.