Dembowsky K, Czachurski J, Seller H
J Auton Nerv Syst. 1985 Jul;13(3):201-44. doi: 10.1016/0165-1838(85)90012-8.
In chloralose anaesthetized, paralyzed and artificially ventilated cats intracellular recordings were obtained from sympathetic preganglionic neurones (SPN) of the third thoracic segment of the spinal cord identified by antidromic stimulation of the white ramus T3. The synaptic input to SPNs was assessed, in cats with intact neuraxis or spinalized at C3, by electrical stimulation of segmental afferent fibres in intercostal nerves and white rami of adjacent thoracic segments and by stimulation of the ipsi- and contralateral dorsolateral funiculus and of the dorsal root entry zone of the cervical spinal cord. In both preparations SPNs showed on-going synaptic activity which predominantly consisted of excitatory post-synaptic potentials (EPSPs). Inhibitory post-synaptic potentials (IPSPs) were rarely observed. EPSPs were single step (5 mV) or, less frequently, large (up to 20 mV) summation EPSPs. The proportion of SPNs showing very low levels of on-going activity was markedly higher in spinal than in intact cats. Stimulation of somatic and sympathetic afferent fibres evoked early EPSPs (amplitude 3 mV, latency 5-22.3 ms), and late, summation EPSPs (amplitude up to 20 mV, latency 27-55 ms). Early and late EPSPs were evoked in nearly all SPNs in which this synaptic input was tested in the intact preparation (from 79-93% of the SPNs). In spinal cats, early EPSPs were evoked in 88% of the SPNs, whereas late EPSPs were recorded only in half of the neurones. No evidence for a monosynaptic pathway from these segmental afferent fibres to SPNs was obtained. In both intact and spinal cats, stimulation of the dorsolateral funiculus evoked early and late EPSPs in SPNs. Late EPSPs were recorded in 70% and 37% of the SPNs in intact and spinal cats, respectively. Early EPSPs, however, were evoked in all neurones. The early EPSPs evoked by stimulation of the dorsolateral funiculus had several components which are suggested to arise from stimulation of descending excitatory pathways with different conduction velocities. The following conduction velocities were calculated in intact (spinal) cats: 9.5-25 m/s (7.8-13.2 m/s), 5.7-9.5 m/s (5.5-7.8 m/s), 3.8-5.7 m/s (3.2-5.5 m/s), and 2.6-3.8 m/s (2.1-3.2 m/s). EPSPs of these various groups were elicited in a varying percentage in SPNs. EPSPs of the most rapidly conducting pathway were subthreshold for the generation of action potentials; some EPSPs of this group had a constant latency suggesting a monosynaptic pathway to SPNs. Stimulation of the dorsal root entry zone at the cervical level yielded essentially the same results as stimulation of the dorsolateral funiculus.(ABSTRACT TRUNCATED AT 400 WORDS)
在氯醛糖麻醉、麻痹并人工通气的猫身上，通过对T3白交通支进行逆向刺激，从脊髓第三胸段的交感神经节前神经元（SPN）获得细胞内记录。在神经轴完整或C3水平脊髓横断的猫中，通过电刺激肋间神经和相邻胸段白交通支的节段性传入纤维，以及刺激同侧和对侧背外侧索和颈脊髓背根进入区，来评估SPN的突触输入。在这两种制备中，SPN均表现出持续的突触活动，主要由兴奋性突触后电位（EPSP）组成。很少观察到抑制性突触后电位（IPSP）。EPSP为单步（5 mV），或较少见的大（高达20 mV）总和EPSP。脊髓猫中显示持续活动水平极低的SPN比例明显高于完整猫。刺激躯体和交感传入纤维诱发早期EPSP（幅度3 mV，潜伏期5 - 22.3 ms）和晚期总和EPSP（幅度高达20 mV，潜伏期27 - 55 ms）。在完整制备中测试这种突触输入的几乎所有SPN中（79 - 93%的SPN）都诱发了早期和晚期EPSP。在脊髓猫中，88%的SPN诱发了早期EPSP，而仅在一半的神经元中记录到晚期EPSP。未获得从这些节段性传入纤维到SPN的单突触通路的证据。在完整和脊髓猫中，刺激背外侧索均在SPN中诱发早期和晚期EPSP。在完整和脊髓猫中，分别有70%和37%的SPN记录到晚期EPSP。然而，所有神经元均诱发了早期EPSP。刺激背外侧索诱发的早期EPSP有几个成分，提示它们源于不同传导速度的下行兴奋性通路的刺激。在完整（脊髓）猫中计算出以下传导速度：9.5 - 25 m/s（7.8 - 13.2 m/s）、5.7 - 9.5 m/s（5.5 - 7.8 m/s）、3.8 - 5.7 m/s（3.2 - 5.5 m/s）和2.6 - 3.8 m/s（2.1 - 3.2 m/s）。这些不同组别的EPSP在SPN中以不同百分比诱发。传导最快通路的EPSP对于动作电位的产生为阈下；该组中的一些EPSP具有恒定潜伏期，提示存在到SPN的单突触通路。刺激颈段背根进入区产生的结果与刺激背外侧索基本相同。（摘要截断于400字）
