title: Membrane properties related to the firing behavior of zebrafish motoneurons.
abstract: The physiological and pharmacological properties of the motoneuron membrane and action potential were investigated in larval zebrafish using whole cell patch current-clamp recording techniques. Action potentials were eliminated in tetrodotoxin, repolarized by tetraethylammonium (TEA) and 3,4-diaminopyridine (3,4-AP)-sensitive potassium conductances, and had a cobalt-sensitive, high-threshold calcium component. Depolarizing current injection evoked a brief (approximately 10-30 ms) burst of action potentials that was terminated by strong, outwardly rectifying voltage-activated potassium and calcium-dependent conductances. In the presence of intracellular cesium ions, a prolonged plateau potential often followed brief depolarizations. During larval development (hatching to free-swimming), the resting membrane conductance increased in a population of motoneurons, which tended to reduce the apparent outward rectification of the membrane. The conductances contributing to action potential burst termination are hypothesized to play a role in patterning the synaptically driven motoneuron output in these rapidly swimming fish.
authors.affiliation: McGill Centre for Research in Neuroscience and Department of Biology, McGill University, Montreal, H3G 1A4 Quebec, Canada.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Buss
authors.forename: Charles W
authors.initials: CW
authors.lastname: Bourque
authors.forename: Pierre
authors.initials: P
authors.lastname: Drapeau
mesh_terms: D015761:4-Aminopyridine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000077770:Amifampridine; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D015220:Calcium Channels / Q000502:physiology; D003035:Cobalt / Q000494:pharmacology; D009046:Motor Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology; D015222:Sodium Channels / Q000502:physiology; D013550:Swimming / Q000502:physiology; D019789:Tetraethylammonium / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D015027:Zebrafish
chemical_list: D000779:Anesthetics, Local; D015220:Calcium Channels; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D015222:Sodium Channels; D003035:Cobalt; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D000077770:Amifampridine