An in vitro investigation of the action of ketamine on excitatory synaptic transmission in the hippocampus of the guinea-pig.
The effect of ketamine on excitatory synaptic transmission was examined in vitro in slices of guinea-pig hippocampus. Ketamine (100-500 microM) depressed the amplitude of the field excitatory post-synaptic potential (e.p.s.p.) and the population spike evoked in the dentate gyrus by stimulation of the perforant path. It did not affect the coupling between the e.p.s.p. and the population spike. Ketamine (0.2 mM) had no consistent depolarizing or hyperpolarizing effect on the resting membrane potential of the granule cells nor did it alter their input resistance. It did, however, reduce the amplitude of the intracellularly recorded e.p.s.p. Ketamine (5-200 microM) reduced the sensitivity of the granule cells to 1-glutamate applied iontophoretically but did not significantly depress the potassium-stimulated efflux of [3H]glutamate from synaptosomes. It is concluded that ketamine depresses excitatory synaptic transmission in the dentate gyrus by depressing chemical transmission probably via a post-synaptic mechanism.
Oshima
E
E
Department of Physiology, Royal Free Hospital School of Medicine, London, U.K.
Richards
C D
CD
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D007478:Iontophoresis; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D013569:Synapses / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects*; D013574:Synaptosomes / Q000187:drug effects
D007649:Ketamine