大鼠“膀胱经”上A-类初级传入纤维在跨节段信息传递中的电生理特性

The properties of primary afferent A-fibers in conduction across adjacent spinal segments along urinary bladder meridian in rats

目的 分析经脉线上初级传入神经参与跨脊髓节段信息传递的成分及其相关机制。方法 在 6 7只大鼠胸 9～ 1 2 (T9～1 2 )脊神经背侧皮支上分离细束 ,用电生理学方法观察了 1 47个A类初级传入纤维 (包括Aβ 和Aδ 两类 )的放电及其相关特性 ,电刺激相邻节段神经干后传入放电的改变。结果 1 3个Aβ 类单位的平均传导速度为 (3 3 84± 1 46 )m/s;全部为快适应单位 ,平均电刺激阈值 0 2 7mA ,5 4 6 % (7/1 3 )的单位有低频自发放电 ,每 3 0s平均放电数为 1 3 1±0 2 0 ,跨节段电刺激后 ,放电无明显改变。 1 3 4个Aδ 类单位的平均传导速度 (1 3 5 1± 0 78)m/s,其中快适应单位 5 5个 ,慢适应单位 79个 ;平均电刺激阈值 0 2 2mA ,跨节段电刺激后 ,两种适应单位中被兴奋单位所占比例差异显著 ,P <0 0 0 5。 41 1 % (5 5 /1 3 4 )的Aδ 单位有散在而不规律的自发放电 ,每 3 0s平均放电数 0 73± 0 1 4。跨节段电刺激后 5 6 0 % (75 /1 3 4 )的单位放电迅速增加 ,在电刺激后 3 0s内达高峰 ,0～ 3 0s、3 0～ 6 0s、6 0～ 90s的平均放电数分别为 2 5 4±0 85、1 87± 0 5 2、1 49± 0 41 ,显著高于跨节段电刺激前 (P <0 0 0 1或 0 0 5 )。结论 A类初级传入纤维参与了外周末梢之间的跨节?

Objective In order to clarify the classes of primary afferent fibers participating in the information conduction across spinal segments and to observe their discharge property. Methods The dorsal cutaneous nerve branches of spinal nerves from T 8-11 segments innervating the urinary bladder meridian were cut proximally. One peripheral end of the cut nerves was dissected into a few filaments for recording single fiber while the adjacent one for antidromical electrical stimulation, both by platinum bipolar electrodes.Results When a train of 20 Hz, 0.1 ms width square waves of 10 s was delivered to the nerve for stimulation, the discharge of the A δ-fiber of the adjacent nerve showed a remarkable increase, reached it's maximum within 30 s after stimulation, maintained for 90 s( P <0.001, 0.05), then returned to the control level 90 s later. This change was induced more easily in the slowly adapting units with slower conductive velocity.Conclusion This results suggest that A δ-fibers innervating urinary bladder meridian involve in the information transmission between peripheral sensory nerve endings of adjacent spinal segments. That may be one of the important mechanism of the sensory conduction along meridian.