Partial reversal of conduction slowing during repetitive stimulation of single sympathetic efferents in human skin
Partial reversal of conduction slowing during repetitive stimulation of single sympathetic efferents in human skin
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DOI：
10.1111/j.1365-201x.2004.01357.x
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发表时间：
2004-11-01
期刊：
影响因子：
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通讯作者：
Ochoa, JL
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文献类型：
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作者：
Campero, M;Serra, J;Ochoa, JL
目的：描述和识别一类对重复电刺激有异常反应的人类C纤维的功能。其他C纤维在2 Hz时逐渐减慢（1型），达到潜伏期平台（2型）或几乎不减慢（3型）。方法：用显微神经摄影技术记录19名健康志愿者腓浅神经支配多毛皮肤的C纤维。基线电刺激的皮肤是在0.25 Hz，和活动依赖性放缓记录在2 Hz的刺激3 min，并在3 min的暂停后，在stimulation.Results：在41个单位，有部分恢复的潜伏期在重复刺激。这些被归类为“4型”单位，并确定为交感神经传出，因为他们表现出自发活动，这是增强的演习，增加交感神经流出（15 16例）和/或抑制近端麻醉阻滞（8例）。在2 Hz序列期间的峰值减慢平均为6.47 +/- 2.06%（平均值+/- SD，n = 41），但在3分钟后减慢降低至4.90 +/-2.20%，这低于所有1型（伤害感受器）纤维，但与2型（冷）纤维相似。与冷纤维相比，4型交感神经纤维在2 Hz的前10个脉冲后减慢得更多（2.57 +/- 0.45%）以及刺激暂停后（1.66 +/- 0.51%）。这些4型交感神经C单位独特的活动依赖性减慢曲线可能有助于体外识别，并表明超极化激活通道在轴突膜中具有特别突出的作用。
Aims: To describe and identify the function of a class of human C fibre with an unusual response to repetitive electrical stimulation. Other C fibres slow progressively at 2 Hz (type 1), reach a latency plateau (type 2) or hardly slow at all (type 3).Methods: C fibres innervating hairy skin were recorded by microneurography in the superficial peroneal nerves of 19 healthy volunteers. Baseline electrical stimulation of the skin was at 0.25 Hz, and activity-dependent slowing recorded during stimulation at 2 Hz for 3 min and after a 3-min pause in stimulation.Results: In 41 units, there was a partial recovery of latency during repetitive stimulation. These were classified as 'type-4' units, and identified as sympathetic efferents, since they exhibited spontaneously activity, which was enhanced by manoeuvres that increase sympathetic outflow (15 of 16 cases) and/or suppressed by a proximal anaesthetic block (eight of eight cases). The peak slowing during 2 Hz trains averaged 6.47 +/- 2.06% (mean +/- SD, n = 41), but after 3 min the slowing had reduced to 4.90 +/- 2.20%, which was less than in all type 1 (nociceptor) fibres but similar to that in type 2 (cold) fibres. Compared with cold fibres, type-4 sympathetic fibres slowed more after the first 10 impulses at 2 Hz (2.57 +/- 0.45%) and also after a pause in stimulation (1.66 +/- 0.51%).Conclusions: The distinctive activity-dependent slowing profiles of these type-4 sympathetic C units may help identification in vitro, and suggest that hyperpolarization-activated channels have a particularly prominent role in the axonal membrane.