Shyu B C, Olausson B, Huang K H, Widerström E, Andersson S A
Department of Physiology, Gothenburg University, Sweden.
Acta Physiol Scand. 1989 Sep;137(1):73-84. doi: 10.1111/j.1748-1716.1989.tb08722.x.
Unmyelinated C-fibre responses to electrical stimulation were recorded in common peroneal, sural and tibial nerves of rabbits. Three distinct C elevations, here called C1, C2 and C3, were recorded. C2 is probably of somatic origin because it was depressed due to collision by peripheral stimulation of cutaneous receptors. The conduction velocity of C3 corresponded to that of sympathetic post-ganglionic fibres. During sympathetic trunk stimulation the A-fibre responses were not significantly changed while C responses, especially C2, were reduced in amplitude and slightly delayed. The C-fibre responses were also influenced by intra-arterial infusion of noradrenaline. In most cases, the latency of the response was increased. The effect of sympathetic stimulation was completely blocked by hexamethonium, and partly blocked by phentolamine, an adrenergic alpha-receptor blocking agent which also blocked the effect of noradrenaline. The findings suggest that there are adrenergic receptors distributed along unmyelinated somatic afferent fibres. Sympathetic activity may release noradrenaline in the peripheral nerve, resulting in changed conductive properties in unmyelinated fibres transmitting sensory information.
在兔的腓总神经、腓肠神经和胫神经中记录了无髓鞘C纤维对电刺激的反应。记录到三个不同的C波峰，这里称为C1、C2和C3。C2可能起源于躯体，因为它会因皮肤感受器的外周刺激碰撞而受到抑制。C3的传导速度与交感神经节后纤维的传导速度相当。在交感干刺激期间，A纤维反应没有明显变化，而C纤维反应，尤其是C2，振幅减小且略有延迟。C纤维反应也受到动脉内注射去甲肾上腺素的影响。在大多数情况下，反应潜伏期延长。交感刺激的作用被六甲铵完全阻断，部分被酚妥拉明阻断，酚妥拉明是一种肾上腺素能α受体阻断剂，它也阻断了去甲肾上腺素的作用。这些发现表明，无髓鞘躯体传入纤维上分布有肾上腺素能受体。交感神经活动可能在外周神经中释放去甲肾上腺素，导致在传递感觉信息的无髓鞘纤维中传导特性发生改变。
