The slow inhibitory postsynaptic potential in rat hippocampal CA1 neurones is blocked by intracellular injection of QX-314.
Intracellular recordings were made from CA1 pyramidal neurones in the rat hippocampus slice preparation. The recording electrodes contained potassium acetate (4 M) with or without the quaternary lidocaine derivative, QX-314 (50 mM). Both fast (f) and slow (s) inhibitory postsynaptic potentials (IPSP) were evoked by low-frequency orthodromic stimulation. The s-IPSP was rapidly reduced by QX-314 injection. It decreased along a similar time course to the dV/dt of the action potential (AP). The f-IPSP and excitatory postsynaptic potential were not significantly reduced in size at a time when the s-IPSP was virtually abolished by QX-314. It is concluded that conductance through the K+ channels which are coupled to GABAB receptors is readily blocked by QX-314, while the Cl- channels which are coupled to GABAA receptors and the cation channels coupled to the glutamate receptors are relatively resistant to the local anaesthetic.
Nathan
T
T
PharmaBiotic Research Centre, University of Aarhus, Denmark.
Jensen
M S
MS
Lambert
J D
JD
D000200:Action Potentials / Q000187:drug effects; D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D004558:Electric Stimulation; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D000777:Anesthetics; D015221:Potassium Channels; C012647:QX-314; D008012:Lidocaine