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Titolo:
ELECTROPHYSIOLOGICAL PROPERTIES OF GUINEA-PIG TRIGEMINAL MOTONEURONS RECORDED IN-VITRO
Autore:
CHANDLER SH; HSAIO CF; INOUE T; GOLDBERG LJ;
Indirizzi:
UNIV CALIF LOS ANGELES,DEPT PHYSIOL SCI,2851 SLICHTER HALL LOS ANGELES CA 90024 UNIV CALIF LOS ANGELES,SCH DENT LOS ANGELES CA 90024
Titolo Testata:
Journal of neurophysiology
fascicolo: 1, volume: 71, anno: 1994,
pagine: 129 - 145
SICI:
0022-3077(1994)71:1<129:EPOGTM>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
HYPOGLOSSAL NEURONS INVITRO; RHYTHMICAL JAW MOVEMENTS; VOLTAGE-CLAMP; HORSERADISH-PEROXIDASE; INTRACELLULAR ANALYSIS; SPINAL MOTONEURONES; MEMBRANE CURRENTS; FIRING PROPERTIES; OUTWARD CURRENTS; RAT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
51
Recensione:
Indirizzi per estratti:
Citazione:
S.H. Chandler et al., "ELECTROPHYSIOLOGICAL PROPERTIES OF GUINEA-PIG TRIGEMINAL MOTONEURONS RECORDED IN-VITRO", Journal of neurophysiology, 71(1), 1994, pp. 129-145

Abstract

1. Intracellular recording and stimulation were made from guinea pig trigeminal motoneurons (TMNs) in brain stem slices. Electrophysiological properties were examined and the underlying currents responsible for motoneuron excitability were investigated by the use of current clamp and single electrode voltage clamp (SEVC) techniques. 2. The voltageresponses to subthreshold hyperpolarizing or depolarizing current pulses showed voltage- and time-dependent inward rectification. SEVC analysis demonstrated that the hyperpolarizing inward rectification resulted from the development of a slowly occurring voltage-dependent inwardcurrent activated at hyperpolarized membrane potentials. This currentpersisted in solutions containing low Ca2+/Mn2+, tetraethylammonium (TEA), and Ba2+, whereas it was reduced by 1-3 mM cesium. The depolarizing inward rectification was mediated by a persistent sodium current (I-Na-P) that was completely abolished by bath application of tetrodotoxin (TTX). 3. Action potential characteristics were studied by intracellular stimulation with brief current pulses (<3 ms) in combination with ionic substitutions or application of specific ionic conductance blocking agents. Bath application of TTX abolished the action potential,whereas 1-10 mM TEA or 0.5-2 mM 4-aminopyridine (4-AP) increased, significantly, the spike duration, suggesting participation of the delayed rectifier and A-current type conductances in spike repolarization. SEVC analysis revealed a TEA-sensitive sustained outward current and a fast, voltage-dependent, transient current with properties consistent with their roles in spike repolarization. 4. TMN afterhyperpolarizing potentials (AHPs) that followed a single spike consisted of fast and slow components usually separated by a depolarizing hump [afterdepolarization (ADP)]. The fast component was abolished by TEA or 4-AP but notby Mn2+ Co2+, or the bee venom apamin. In contrast, the slow AHP was readily reduced by Mn2+, Co2+, or apamin, suggesting participation of an apamin-sensitive, calcium-dependent K+ conductance in the production of the slow AHP. SEVC analysis and ionic substitutions demonstrated a slowly activating and deactivating calcium-dependent K+ current withproperties that could account for the slow AHP observed in these neurons. 5. Repetitive discharge was examined with long depolarizing current pulses (1 s) and analysis of frequency-current plots. When evoked from resting potential (about -55 mV), spike onset from rheobase occurred rapidly and was maintained throughout the current pulse. At higher current intensities, early and late adaptations in spike discharge were observed. Frequency-current plots exhibited a bilinear relationship for the first interspike interval (ISI) in similar to 50% of the neurons tested and in most neurons tested during steady-state discharge (SS). The mean slopes for the first ISI of the primary and secondary range firings were 56 and 117 Hz/nA and 16 Hz/nA for the primary range during SS discharge. 6. Bath application of inorganic calcium channel blockers (Mn2+, Co2+) or apamin increased the maximum SS frequency and slope of the frequency-current plots for all neurons tested, suggesting a role for a calcium-dependent K+ conductance in control of repetitivedischarge. 7. The present study indicates that intrinsic cellular properties, in addition to timing of synaptic inputs, must be considered when discussing the factors that control motoneuronal excitability andburst-pattern formation during jaw movements.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/11/20 alle ore 18:47:36