title: Voltage-clamp analysis of a self-inhibitory synaptic potential in the buccal ganglia of Aplysia.
abstract: 1. In cholinergic neurones BL4, BL5, BR4, and BR5 of Aplysia buccal ganglia, each action potential is followed, in the same cell, by a curare- and high-Mg-sensitive hyperpolarizing after-potential which is enhanced by Ca. 2. In voltage-clamped neurons, substracting currents recorded in curare from currents recorded in sea water reveals that this potential is due to curare-sensitive currents which rise to a peak, then decay exponentially with an apparently voltage-independent time constant of 43 msec. Currents are produced by a voltage-independent, Ca-enhanced, conductance change with a 0-26 mumho peak and a -64 mV reversal potential. The curare-sensitive conductance is also sensitive to high Mg. 3. Both after-potential and curare- or Mg-sensitive current follow each action potential without failures, even in threshold-raising 80 mM-Ca-144-mM-Mg solutions. 4. Both after-potential and current decrease with repetitive firing or short inter-spike interval, possibly due to receptor desensitization. 5. The Mg- and curare-sensitive conductance is also blocked by 1 mM-ACh. 6. The data are consistent with the hypothesis that the hyperpolarization following action potentials in each of these four neurones is produced by a self-inhibitory synaptic mechanism.
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004553:Electric Conductivity; D005724:Ganglia / Q000502:physiology*; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008974:Mollusca / Q000502:physiology*; D009433:Neural Inhibition; D009474:Neurons / Q000502:physiology; D011950:Receptors, Cholinergic; D013569:Synapses / Q000502:physiology*; D014403:Tubocurarine / Q000494:pharmacology
chemical_list: D011950:Receptors, Cholinergic; D008274:Magnesium; D002118:Calcium; D014403:Tubocurarine