Inhibitory postsynaptic currents at Aplysia cholinergic synapses: Effects of permeant anions and depressant drugs

D. J. Adams, P. W. Gage, O. P. Hamill

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Inhibitory postsynaptic potentials ( and, under voltage-clamp conditions, inhibitory postsynaptic currents (i.p.s.cs) were recorded in neurons in buccal ganglia of Aplysia juliana. the decay of i.p.s.cs was exponential with a single time constant, τ, which decreased with membrane depolarization. In external solutions containing iodide or bromide ions instead of chloride ions, τ varied according to the sequence τ(I)>τ(Br)>τ(Cl), and the voltage sensitivity of τ was altered. In iodide solution, the voltage sensitivity of τ was reversed. Furthermore, the foreign halides depressed the peak current amplitude and shifted the reversal (zero-current) potential to more positive membrane potentials. In low concentrations of sodium pentobarbitone (100-200 μM), the decay of i.p.s.cs became biphasic. Increasing drug concentration and membrane hyperpolarization had differential effects on the rates and relative amplitudes of the two components of i.p.s.c. decay. Octanol (0.5-1 mM) reduced the amplitude of and increased the rate of decay of i.p.s.cs without changing the voltage sensitivity of τ. The effect of foreign halides and barbiturates on i.p.s.c. decay were interpreted in terms of a reaction between the anion and an ion-binding site(s) associated with the anion-selective channel, which affects the probability of anions entering the channel and normal channel closure.

Original languageEnglish (US)
Pages (from-to)335-350
Number of pages16
JournalProceedings of the Royal Society of London - Biological Sciences
Issue number1196
StatePublished - 1982
Externally publishedYes

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences
  • General Environmental Science
  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology


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