title: Action of alpha-dendrotoxin on K+ currents in nerve terminal regions of axons in rat olfactory cortex.
abstract: 1. In the rat olfactory cortex, unmyelinated axons give rise to synapses en passant. This tissue was used to study the pharmacology of axonal K(+)-currents. Responses were measured from a group of these axons as unclamped field currents, with a polarizable suction electrode. 2. A single stimulus to the axons elicited a tetrodotoxin-sensitive Na(+)-dependent transient K(+)-currents were revealed by positive polarization of the suction electrode and were manifest as a negative current following the Na(+)-component. 3. In the presence of tetraethylammonium (TEA, 5 mM) and Cd2+ (100 microM), the K(+)-component was depressed by 3,4-diaminopyridine (3,4-DAP; 1 to 20 microM; IC50 2.0 +/- 0.4 microM). alpha-Dendrotoxin (DTX; 15-1500 nM) also attenuated the aminopyridine-sensitive component (IC50 93 +/- 4 nM). At the highest DTX concentration, depression of the K(+)-current was incomplete, the residual K+ current being reduced by 3,4-DAP (0.1 to 5 microM). 4. These results indicate the presence of two aminopyridine-sensitive K+ currents in this preparation distinguished by their susceptibility to DTX.
authors.affiliation: School of Biomedical Science, Queen's University, Belfast, UK.
authors.forename: J
authors.initials: J
authors.lastname: McGivern
authors.forename: C N
authors.initials: CN
authors.lastname: Scholfield
authors.forename: J O
authors.initials: JO
authors.lastname: Dolly
mesh_terms: D015761:4-Aminopyridine / Q000031:analogs & derivatives / Q000494:pharmacology; D000077770:Amifampridine; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism*; D002104:Cadmium / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D004546:Elapid Venoms / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D009186:Myelin Sheath / Q000502:physiology; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism*; D009498:Neurotoxins / Q000494:pharmacology*; D009830:Olfactory Bulb / Q000187:drug effects / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
chemical_list: D004546:Elapid Venoms; D009498:Neurotoxins; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D002104:Cadmium; C020273:dendrotoxin; D012964:Sodium; D015761:4-Aminopyridine; D000077770:Amifampridine