title: Internal presynaptic tetraethylammonium (TEA+) blocks cholinergic transmission at a synapse between identified neurones.
abstract: Intracellular microelectrodes were used to study a cholinergic synapse between two identified neurones: the lateral filiform hair sensory neurone (LFHSN) and giant interneurone 3 (GI 3) in the terminal ganglion of the first-instar cockroach Periplaneta americana. The presynaptic neurone (LFHSN) was impaled in a region of the axon which forms large numbers of output synapses onto GI 3. Intracellular injection of tetraethylammonium (TEA+) into LFHSN blocked LFHSN-GI 3 synaptic transmission. Injection of TEA+ and either acetylcholine (ACh) or choline into the axon preserved synaptic transmission. TEA+ may compete with choline at an intracellular site involved in the maintenance of releaseable ACh.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002799:Cholinergic Fibers / Q000502:physiology*; D008839:Microelectrodes; D010526:Periplaneta; D013569:Synapses / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*
chemical_list: D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D000109:Acetylcholine