XXXX channel involvement in GABAB receptor-mediated inhibition of @entity1246 release in area @entity1249 of the @entity35 hippocampus.

@entity7236 @entity1246 @entity1249 @entity1022 @entity3409 @entity460 @entity972 @entity35 @entity1772
1. Experiments were performed in @entity35 hippocampal slices to examine the nature of GABAergic inhibition of inhibitory synaptic transmission. In these experiments the effects of the @entity1246 -B (GABAB) receptor agonist, @entity1772 , and of subtype-selective @entity460 channel blockers were tested with the use of intracellular recordings of evoked inhibitory postsynaptic potentials (IPSPs) and whole cell recordings of spontaneous GABAergic inhibitory postsynaptic currents (IPSCs). 2. @entity1772 inhibited evoked and spontaneous (action-potential-dependent) monosynaptic GABAA-mediated IPSPs and IPSCs but had no effect on the frequency of @entity1022 -resistant (action-potential-independent) miniature IPSCs recorded in @entity1249 pyramidal neurons. 3. Depolarizing GABAergic synaptic terminals by raising the extracellular @entity972 concentration caused an increase in action-potential-independent miniature IPSC frequency that could be inhibited by either @entity1772 or @entity3409 , a blocker of voltage-dependent @entity460 channels. In addition, under these depolarizing conditions, @entity3409 occluded the @entity1772 inhibition of miniature IPSCs. These data suggest that @entity1772 reduces only depolarization-induced, not quantal, @entity1246 release and that it does so by decreasing presynaptic voltage-dependent @entity460 influx. 4. Experiments with subtype-selective @entity460 channel blockers demonstrate that the presynaptic action of @entity1772 was mediated through both omega-conotoxin-GVIA-sensitive and omega-agatoxin-IVA-sensitive, but not @entity7236 -sensitive @entity460 channels.
