Petsche U, Fleischer E, Lembeck F, Handwerker H O
Brain Res. 1983 Apr 18;265(2):233-40. doi: 10.1016/0006-8993(83)90337-2.
Capsaicin applied locally to a coccygeal or saphenous nerve of rats was shown to block impulse conduction in unmyelinated afferent nerve fibres. Shortly after application of capsaicin (1% dissolved in 10% Tween 80 in paraffin oil) conduction of C-fibre--but not A-fibre--compound action potentials across the application site was markedly diminished. No recovery occurred during the period of observation, i.e. up to 2 h afterwards. C-Fibre compound action potentials stimulated and recorded proximal to the application site seemed to be unaffected. Solvent application had no effect. Recording from single units revealed that nociceptive C-fibres responding to strong mechanical and heat stimulation (MH units, polymodal nociceptors) were blocked. In contrast, unmyelinated cold fibres were not affected. The selective block of MH units indicates different membrane properties of unmyelinated MH and cold units not only at the receptive nerve endings, but also at the axons, to which capsaicin was applied.
研究表明，将辣椒素局部应用于大鼠的尾骨神经或隐神经，可阻断无髓传入神经纤维的冲动传导。在应用辣椒素（1%溶解于石蜡油中的10%吐温80）后不久，通过应用部位的C纤维复合动作电位（而非A纤维复合动作电位）的传导明显减弱。在观察期内，即在此后长达2小时内，未出现恢复。在应用部位近端刺激并记录的C纤维复合动作电位似乎未受影响。应用溶剂则无效果。对单个单位的记录显示，对强机械和热刺激有反应的伤害性C纤维（MH单位，多模式伤害感受器）被阻断。相比之下，无髓冷纤维未受影响。MH单位的选择性阻断表明，无髓MH单位和冷单位不仅在感觉神经末梢，而且在应用辣椒素的轴突处，都具有不同的膜特性。
