Actions of the anaesthetic Saffan on rat sympathetic preganglionic neurones in vitro
Actions of the anaesthetic Saffan on rat sympathetic preganglionic neurones in vitro
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DOI：
10.1038/sj.bjp.0701127
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发表时间：
1997-05-01
影响因子：
7.3
通讯作者：
Logan, SD
中科院分区：
文献类型：
--
作者：
Nolan, MF;Gibson, IC;Logan, SD
1采用全细胞膜片钳记录法研究麻醉剂Saffan对大鼠脊髓切片交感节前神经元（SPNs）电生理特性的影响。2 Saffan（1-54 μ M）消除或降低自发动作电位放电频率，消除自发阈下膜电位振荡。Saffan引起输入电阻的剂量依赖性降低，并取决于初始静息膜电位，去极化、超极化或膜电位无变化。3对Saffan的反应被GABA（A）受体拮抗剂荷包牡丹碱阻断（5-20 μ M）和印防己毒素（20 μ M），但不被甘氨酸受体拮抗剂士的宁（20 μ M）所抑制，表明它们是由GABA介导的（A）受体。4还观察到SPN动作电位特性的变化。在存在Saffan的情况下，动作电位后超极化的幅度和持续时间降低，并且需要更大的去极化以诱发动作电位序列。5为了检查Saffan对SPN之间的电紧张性耦合的影响，在细胞内溶液中使用Na+通道阻断剂QX-314进行实验，并通过腹根刺激诱发逆向振荡。Saffan未能消除逆向振荡，但减少了其幅度和持续时间。这表明自发性膜电位振荡的消除不是对SPN之间耦合的直接影响，而是由于。Saffan对自发活动的消除。6在麻醉期间，对Saffan的反应发生在Saffan的血浆浓度范围内，这表明在Saffan麻醉期间，SPN的电生理特性可能会改变。预计这将导致交感神经紧张和交感神经输出整合的变化。
1 Whole-cell patch-clamp recordings were used to investigate the effects of the anaesthetic Saffan on the electrophysiological properties of sympathetic preganglionic neurones (SPNs) in rat spinal cord slices.2 Saffan (1-54 mu M) abolished or reduced the frequency of spontaneous action potential firing and abolished spontaneous, sub-threshold membrane potential oscillations. Saffan caused dose-dependent decreases in input resistance and depending upon the initial resting membrane potential, either a depolarization, a hyperpolarization or no change in membrane potential.3 Responses ro Saffan were blocked by the GABA(A) receptor antagonists bicuculline (5-20 mu M) and picrotoxin (20 mu M), but not by the glycine receptor antagonist strychnine (20 mu M) indicating that they were mediated by GABA(A) receptors.4 Changes in the properties of SPN action potentials were also observed. In the presence of Saffan the amplitude and duration of the action potential after-hyperpolarization: were reduced and larger depolarizations were required in order to evoke trains of action potentials.5 To examine the effects of Saffan on electrotonic coupling between SPNs, experiments were performed with the Na+ channel blocker QX-314 in the intracellular solution and antidromic oscillations were evoked by ventral root stimulation. Saffan failed to abolish antidromic oscillations, but reduced their amplitude and duration. This indicates that the abolition of spontaneous membrane potential oscillations was not a direct effect on the coupling between SPNs, but was a result of. the abolition of spontaneous activity by Saffan.6 The responses to Saffan occurred within the plasma concentration range of Saffan during anaesthesia, suggesting that the electrophysiological properties of SPNs may be altered during anaesthesia with Saffan. This would be expected to lead to changes in sympathetic tone and in the integration of sympathetic output.