MEMBRANE-PROPERTIES OF RAT SUBSTANTIA GELATINOSA NEURONS INVITRO
MEMBRANE-PROPERTIES OF RAT SUBSTANTIA GELATINOSA NEURONS INVITRO
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DOI：
10.1152/jn.1989.62.1.109
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发表时间：
1989-07-01
影响因子：
2.5
通讯作者：
JESSELL, TM
中科院分区：
文献类型：
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作者：
YOSHIMURA, M;JESSELL, TM
1.用带背根的成年大鼠脊髓横断切片制片，观察了胶状质(SG)神经元的膜特性。从已鉴定的SG神经元获得细胞内记录。2.静息电位超极化时，76%的SG神经元表现出时间依赖性的异常整流。铯(Cs+，2 mM)阻断时间依赖性AR，而Ba2+(Ba2+，2 mM)不阻断。Cs+本身可引起表达时间依赖性AR的SG神经元的膜超极化。静息膜电位以下5~10 mV时，时间依赖性AR的激活最强。3.在少数SG神经元中，尽管在超极化过程中未发现明显的时间依赖性异常整流，但其电流-电压关系仍显示出明显的内向整流。对这些神经元Ba2+和Cs+敏感性的分析证实，SG神经元表达两种不同的ARs，一种是快速和Ba2+敏感的，另一种是时间依赖的和Ba2+不敏感的。4.当超极化电流脉冲的正值大于-60 mV或去极化脉冲的正值大于-65 mV时，51%的SG神经元出现一过性外向整流。在-55 mV的超极化脉冲作用下，瞬时外向整流持续了0.3-2个S。5.瞬时外向整流与膜电阻降低有关，并在低K+溶液中增强。4-氨基吡啶(4-AP，2 mM)可逆地阻断瞬时外向整流。6.时间相关的异常和瞬时外向整流电流对SG神经元的放电特性产生相反的影响。激活时间依赖性AR可增加神经元的兴奋性。在表现出时间依赖性AR的神经元中，膜去极化导致反弹去极化的出现，导致在施加去极化脉冲后仅有很短的延迟的棘波的产生。相反，瞬间外向整流电流对去极化脉冲的反应明显延迟了棘波放电。这一延迟可被应用4-AP阻断。7.脑海马神经元亚群反应特性的多样性可能部分源于膜特性的异质性。
1. The membrane properties of substantia gelatinosa (SG) neurons in an in vitro adult rat transverse spinal cord slice preparation with attached dorsal root have been examined. Intracellular recordings were obtained from identified SG neurons. 2. Seventy-six percent of SG neurons exhibited a time-dependent anomalous rectification (AR) when the membrane was hyperpolarized from the resting potential. The time-dependent AR was blocked by cesium (Cs+, 2 mM) but not by barium (Ba2+, 2 mM). Application of Cs+ itself caused membrane hyperpolarization in those SG neurons that expressed the time-dependent AR. The activation of the time-dependent AR was maximal at potentials 5-10 mV below the resting membrane potential. 3. In a few SG neurons, the current-voltage relationship revealed a marked inward rectification, even though there was no detectable time-dependent anomalous rectification during hyperpolarization. Analysis of the Ba2+- and Cs+-sensitivity of these neurons confirmed that SG neurons expressed two distinct ARs, one of which is fast and Ba2+-sensitive and the other of which is time-dependent and Ba2+-insensitive. 4. Fifty-one percent of SG neurons exhibited a transient outward rectification when hyperpolarizing current pulses were applied from potentials more positive than -60 mV or when depolarizing pulses were applied from potentials more negative than -65 mV. The transient outward rectification persisted for 0.3-2 s when hyperpolarizing pulses were applied at -55 mV. 5. The transient outward rectification was associated with a decrease in membrane resistance and was enhanced in low K+ solutions. 4-aminopyridine (4-AP, 2 mM) reversibly blocked the transient outward rectification. 6. The time-dependent anomalous and transient outward rectifying currents exerted opposite effects on the firing properties of SG neurons. Activation of the time-dependent AR increased neuronal excitability. In neurons that exhibited the time-dependent AR, membrane depolarization caused the appearance of a rebound depolarization that resulted in the generation of spikes with only a short delay after application of the depolarizing pulse. In contrast, the transient outward rectifying current markedly delayed spike firing in response to depolarizing pulses. This delay was blocked by application of 4-AP. 7. The diversity in response properties of subpopulations of SG neurons may result in part from this heterogeneity in membrane properties.