Summary
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1.
The characteristics of long-duration inhibitory postsynaptic potentials (l-IPSPs) which are evoked in rat frontal neocortical neurons by local electrical stimulation were investigated with intracellular recordings from anin vitro slice preparation.
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2.
Stimulation with suprathreshold intensities evoked l-IPSPs with typical durations of 600–900 msec at resting membrane potential. Conductance increases of 15–60% were measured at the peak amplitude of l-IPSPs (150–250 msec poststimulus).
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3.
The duration of the conductance increases during l-IPSPs displayed a significant voltage dependence, decreasing as the membrance potential was depolarized and increasing with hyperpolarization.
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4.
The reversal potential of l-IPSPs is significantly altered by reductions in the extracellular potassium concentration. Therefore it is concluded that l-IPSPs in rat neocortical neurons are generated by the activation of a potassium conductance.
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5.
l-IPSPs exhibit stimulation fatigue. Stimulation with a frequency of 1 Hz produces a complete fatigue of the conductance increases during l-IPSPs after approximately 20 consecutive stimuli. Recovery from this fatigue requires minutes.
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6.
l-IPSPs are not blocked by bicuculline but are blocked by baclofen.
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Howe, J.R., Sutor, B. & Zieglgänsberger, W. Characteristics of long-duration inhibitory postsynaptic potentials in rat neocortical neuronsin vitro . Cell Mol Neurobiol 7, 1–18 (1987). https://doi.org/10.1007/BF00734986
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DOI: https://doi.org/10.1007/BF00734986