Multiple ionic mechanisms mediate inhibition of rat motoneurones by inhalation anaesthetics

被引:70
作者
Sirois, JE
Pancrazio, JJ
Lynch, C
Bayliss, DA
机构
[1] Univ Virginia, Dept Pharmacol, Charlottesville, VA 22908 USA
[2] Univ Virginia, Dept Anesthesiol, Charlottesville, VA 22908 USA
来源
JOURNAL OF PHYSIOLOGY-LONDON | 1998年 / 512卷 / 03期
关键词
D O I
10.1111/j.1469-7793.1998.851bd.x
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
1. We studied the effects of inhalation anaesthetics on the membrane properties of hypoglossal motoneurones in a neonatal rat brainstem slice preparation. 2. In current clamp, halothane caused a membrane hyperpolarization that was invariably associated with decreased input resistance; in voltage clamp, halothane induced an outward current and increased input conductance. Qualitatively similar results were obtained with isoflurane and sevoflurane. 3. The halothane current reversed near the predicted K+ equilibrium potential (E-K) and was reduced in elevated extracellular K+ and in the presence of Ba2+ (2 mM). Moreover, the Ba2+ sensitive component of halothane current was linear and reversed near E-K. The halothane current was not sensitive to glibenclamide or thyrotropin-releasing hormone (TRH). Therefore, the halothane current was mediated, in part, by activation of a Ba2+-sensitive K+ current distinct from the ATP- and neurotransmitter-sensitive K+ currents in hypoglossal motoneurones. 4. Halothane also inhibited I-h, a hyperpolarization-activated cationic current; this was primarily due to a decrease in the absolute amount of current, although halothane also caused a small, but statistically significant, shift in the voltage dependence of I-h activation. Extracellular Cs+ (3 mM) blocked I-h and a component of halothane-sensitive current with properties reminiscent of I-h. 5. A small component of halothane current, resistant to Ba2+ and Cs+, was observed in TTX-containing solutions at potentials depolarized to similar to-70 mV. Partial Na+ substitution by N-methyl-D-glucamine completely abolished this residual current, indicating that halothane also inhibited a TTX-resistant Na+ current active near rest potentials. 6. Thus, halothane activates a Ba2+-sensitive, relatively voltage-independent K+ current and inhibits both I-h and a TTX-insensitive persistent Na+ current in hypoglossal motoneurones. These effects of halothane decrease motoneuronal excitability and may contribute to the immobilization that accompanies inhalation anaesthesia.
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收藏
页码:851 / 862
页数:12
相关论文
共 44 条
[1]   MECHANISMS UNDERLYING EXCITATORY EFFECTS OF THYROTROPIN-RELEASING-HORMONE ON RAT HYPOGLOSSAL MOTONEURONS INVITRO [J].
BAYLISS, DA ;
VIANA, F ;
BERGER, AJ .
JOURNAL OF NEUROPHYSIOLOGY, 1992, 68 (05) :1733-1745
[2]   Neuromodulation of hypoglossal motoneurons: cellular and developmental mechanisms [J].
Bayliss, DA ;
Viana, F ;
Talley, EM ;
Berger, AJ .
RESPIRATION PHYSIOLOGY, 1997, 110 (2-3) :139-150
[3]   CHARACTERISTICS AND POSTNATAL-DEVELOPMENT OF A HYPERPOLARIZATION-ACTIVATED INWARD CURRENT IN RAT HYPOGLOSSAL MOTONEURONS IN-VITRO [J].
BAYLISS, DA ;
VIANA, F ;
BELLINGHAM, MC ;
BERGER, AJ .
JOURNAL OF NEUROPHYSIOLOGY, 1994, 71 (01) :119-128
[4]   MODULATION OF NEONATAL RAT HYPOGLOSSAL MOTONEURON EXCITABILITY BY SEROTONIN [J].
BERGER, AJ ;
BAYLISS, DA ;
VIANA, F .
NEUROSCIENCE LETTERS, 1992, 143 (1-2) :164-168
[5]   Development of hypoglossal motoneurons [J].
Berger, AJ ;
Bayliss, DA ;
Viana, F .
JOURNAL OF APPLIED PHYSIOLOGY, 1996, 81 (03) :1039-1048
[6]   MECHANISMS CONCERNED IN THE DIRECT EFFECT OF ISOFLURANE ON RAT HIPPOCAMPAL AND HUMAN NEOCORTICAL NEURONS [J].
BERGJOHNSEN, J ;
LANGMOEN, IA .
BRAIN RESEARCH, 1990, 507 (01) :28-34
[7]   ISOFLURANE HYPERPOLARIZES NEURONS IN RAT AND HUMAN CEREBRAL-CORTEX [J].
BERGJOHNSEN, J ;
LANGMOEN, IA .
ACTA PHYSIOLOGICA SCANDINAVICA, 1987, 130 (04) :679-685
[8]  
CASON BA, 1994, ANESTHESIOLOGY, V81, P1245, DOI 10.1097/00000542-199411000-00019
[9]   Hypothesis: Inhaled anesthetics produce immobility and amnesia by different mechanisms at different sites [J].
Eger, EI ;
Koblin, DD ;
Harris, RA ;
Kendig, JJ ;
Pohorille, A ;
Halsey, MJ ;
Trudell, JR .
ANESTHESIA AND ANALGESIA, 1997, 84 (04) :915-918
[10]   Cloning, functional expression and brain localization of a novel unconventional outward rectifier K+ channel [J].
Fink, M ;
Duprat, F ;
Lesage, F ;
Reyes, R ;
Romey, G ;
Heurteaux, C ;
Lazdunski, M .
EMBO JOURNAL, 1996, 15 (24) :6854-6862