Tanelian D L
Department of Anesthesia, Stanford University School of Medicine, CA 94305.
Exp Brain Res. 1991;86(2):414-20. doi: 10.1007/BF00228966.
The in vivo rabbit cornea was used to investigate the effect of acetylcholine on "free" nerve endings from A-delta and C-fibers in the long-ciliary (corneal) nerve. Extracellular electrophysiologic recordings were obtained from 67 corneal nerve fibers. Acetylcholine in concentrations of 10(-5) to 10(-3) M stimulated a specific population of these corneal afferents that were not activated by mechanical or thermal stimuli. Their conduction velocity was determined to be 1.14 +/- 0.34 m/s (mean +/- SD). The other three previously characterized corneal nerve populations (mechanical, mechano-heat, and cold) were not stimulated by the cholinergic agonists or antagonists. Acetylcholine sensitive afferents were also stimulated by carbachol (10(-5) to 10(-3) M) and nicotine (10(-6) to 10(-4) M) but not by bethanecol (10(-5) to 10(-3) M). Acetylcholine-induced activity was abolished by d-tubocurare (10(-4) M) and kappa-bungarotoxin (10(-6) M). The cAMP analog 8-bromoadenosine 3'5'-cyclic monophosphate activated the same population of chemosensitive C-fibers as acetylcholine. It is concluded that a specific population of C-fiber afferents exist in the rabbit cornea which are stimulated by acetylcholine possibly acting via a neuronal nicotinic receptor. Physiologically, these nerves may be involved in the production of pain following tissue injury or ischemia.
采用兔活体角膜研究乙酰胆碱对长睫状（角膜）神经中A-δ和C纤维“游离”神经末梢的作用。从67条角膜神经纤维记录细胞外电生理数据。浓度为10^(-5)至10^(-3)M的乙酰胆碱刺激了这些角膜传入神经中的特定群体，这些群体不会被机械或热刺激激活。其传导速度测定为1.14±0.34m/s（平均值±标准差）。其他三个先前已明确特征的角膜神经群体（机械性、机械热觉和冷觉）未被胆碱能激动剂或拮抗剂刺激。乙酰胆碱敏感的传入神经也受到卡巴胆碱（10^(-5)至10^(-3)M）和尼古丁（10^(-6)至10^(-4)M）的刺激，但不受氨甲酰甲胆碱（10^(-5)至10^(-3)M）的刺激。乙酰胆碱诱导的活动被筒箭毒碱（10^(-4)M）和κ-银环蛇毒素（10^(-6)M）消除。环磷酸腺苷类似物8-溴腺苷3',5'-环磷酸激活了与乙酰胆碱相同的化学敏感C纤维群体。得出结论，兔角膜中存在特定群体的C纤维传入神经，它们可能通过神经元烟碱受体被乙酰胆碱刺激。在生理上，这些神经可能参与组织损伤或缺血后疼痛的产生。
