Current and voltage clamp studies of the spike medium afterhyperpolarization of hypoglossal motoneurons in a rat brain stem slice preparation

被引:65
作者
Lape, R [1 ]
Nistri, A
机构
[1] SISSA, Biophys Sector, I-34014 Trieste, Italy
[2] SISSA, INFM Unit, I-34014 Trieste, Italy
关键词
D O I
10.1152/jn.2000.83.5.2987
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Whole-cell patch clamp recordings were performed on hypoglossal motoneurons (HMs) in a brain stem slice preparation from the neonatal rat. The medium afterhyperpolarization (mAHP) was the only afterpotential always present after single or multiple spikes, making it suitable for studying its role in firing behavior. At resting membrane potential (-68.8 +/- 0.7 mV), mAHP (23 +/- 2 ms rise-time and 150 +/- 10 ms decay) had 9.5 +/- 0.7 mV amplitude, was suppressed in Ca2+-free medium or by 100 nM apamin, and reversed at -94 mV membrane potential. These observations suggest that mAHP was due to activation of Ca2+-dependent, SK-type K+ channels. Carbachol (10-100 mu M) reversibly and dose dependently blocked the mAHP and depolarized HMs (both effects prevented by 10 mu M atropine). Similar mAHP block was produced by muscarine (50 mu M) In control solution a constant current pulse (1 s) induced HM repetitive firing with small spike frequency adaptation. When the mAHP was blocked by apamin, the same current pulse evoked much higher frequency firing with strong spike frequency adaptation. Carbachol also elicited faster firing and adapting behavior. Voltage clamp experiments demonstrated a slowly deactivating, apamin-sensitive K+ current (l(AHP)) which could account for the mAHP. l(AHP) reversed at -94 mV membrane potential, was activated by depolarization as short as 1 ms, decayed with a time constant of 154 +/- 9 ms at -50 mV, and was also blocked by 50 mu M carbachol. These data suggest that mAHP had an important role in controlling firing behavior as clearly demonstrated after its pharmacological block and was potently modulated by muscarinic receptor activity.
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页码:2987 / 2995
页数:9
相关论文
共 48 条
[1]   PHARMACOLOGICAL INHIBITION OF THE M-CURRENT [J].
ADAMS, PR ;
BROWN, DA ;
CONSTANTI, A .
JOURNAL OF PHYSIOLOGY-LONDON, 1982, 332 (NOV) :223-262
[2]   FIRING BEHAVIOR OF A NEURON MODEL BASED ON AFTERHYPERPOLARIZATION CONDUCTANCE TIME COURSE AND ALGEBRAICAL SUMMATION ADAPTATION AND STEADY-STATE FIRING [J].
BALDISSERA, F ;
GUSTAFSSON, B .
ACTA PHYSIOLOGICA SCANDINAVICA, 1974, 92 (01) :27-47
[3]   VOLTAGE-SENSITIVE OUTWARD CURRENTS IN CAT MOTO-NEURONS [J].
BARRETT, EF ;
BARRETT, JN ;
CRILL, WE .
JOURNAL OF PHYSIOLOGY-LONDON, 1980, 304 (JUL) :251-276
[4]   INHIBITION OF N-TYPE AND P-TYPE CALCIUM CURRENTS AND THE AFTER HYPERPOLARIZATION IN RAT MOTONEURONS BY SEROTONIN [J].
BAYLISS, DA ;
UMEMIYA, M ;
BERGER, AJ .
JOURNAL OF PHYSIOLOGY-LONDON, 1995, 485 (03) :635-647
[5]   Presynaptic depression of excitatory synaptic inputs to rat hypoglossal motoneurons by muscarinic M2 receptors [J].
Bellingham, MC ;
Berger, AJ .
JOURNAL OF NEUROPHYSIOLOGY, 1996, 76 (06) :3758-3770
[6]   IONIC MECHANISMS OF CHOLINERGIC EXCITATION IN MAMMALIAN HIPPOCAMPAL PYRAMIDAL CELLS [J].
BENARDO, LS ;
PRINCE, DA .
BRAIN RESEARCH, 1982, 249 (02) :333-344
[7]   2 COMPONENTS OF MUSCARINE-SENSITIVE MEMBRANE CURRENT IN RAT SYMPATHETIC NEURONS [J].
BROWN, DA ;
SELYANKO, AA .
JOURNAL OF PHYSIOLOGY-LONDON, 1985, 358 (JAN) :335-363
[8]   2 CALCIUM-ACTIVATED POTASSIUM CONDUCTANCES IN A SUBPOPULATION OF CELIAC NEURONS OF GUINEA-PIG AND RABBIT [J].
CASSELL, JF ;
MCLACHLAN, EM .
JOURNAL OF PHYSIOLOGY-LONDON, 1987, 394 :331-349
[9]   ELECTROPHYSIOLOGICAL PROPERTIES OF GUINEA-PIG TRIGEMINAL MOTONEURONS RECORDED IN-VITRO [J].
CHANDLER, SH ;
HSAIO, CF ;
INOUE, T ;
GOLDBERG, LJ .
JOURNAL OF NEUROPHYSIOLOGY, 1994, 71 (01) :129-145
[10]   CARBACHOL POTENTIATES Q-CURRENT AND ACTIVATES A CALCIUM-DEPENDENT NONSPECIFIC CONDUCTANCE IN RAT HIPPOCAMPUS IN-VITRO [J].
COLINO, A ;
HALLIWELL, JV .
EUROPEAN JOURNAL OF NEUROSCIENCE, 1993, 5 (09) :1198-1209