Vizi E S, Gyires K, Somogyi G T, Ungváry G
Neuroscience. 1983 Nov;10(3):967-72. doi: 10.1016/0306-4522(83)90234-8.
Release of acetylcholine from isolated preganglionic axons of sympathetic nerve trunk (cervical preganglionic sympathetic branch) of the cat was studied. In response to depolarization (KCl, 48.4 mM) acetylcholine was released into the eserinized Krebs solution. This release was shown to be dependent on extracellular Ca2+. Electrical stimulation (1 Hz) enhanced the release of acetylcholine from the isolated axonal preparation. The release by stimulation proved to be tetrodotoxin-sensitive and Ca2+-dependent. Evidence has been obtained that the acetylcholine released from sympathetic nerve trunks originates from the axon and not from Schwann cells: 5 days after section of the nerve, there was no release in response to stimulation. The release of acetylcholine from the axon is unlike that from axon terminals in that the rate of release cannot be enhanced by the inhibition of Na, K-adenosine 5'-triphosphatase (ouabain 2 X 10(-5) M) and cannot be modulated by noradrenaline (10(-6) M) or by morphine. Furthermore, although isolated nerve trunks took up [3H]choline by a hemicholinium-sensitive process, no radioactivity could be released upon electrical stimulation. It is suggested that the release of acetylcholine is not confined to axon terminals, but that it can be non-synaptically released by depolarization from axons provided Ca2+ is present.
对猫交感神经干（颈前神经节交感支）分离出的节前轴突乙酰胆碱的释放进行了研究。响应去极化（48.4 mM氯化钾），乙酰胆碱被释放到加入毒扁豆碱的 Krebs 溶液中。这种释放被证明依赖于细胞外钙离子。电刺激（1 Hz）增强了分离出的轴突制剂中乙酰胆碱的释放。刺激引起的释放被证明对河豚毒素敏感且依赖于钙离子。已获得证据表明，交感神经干释放的乙酰胆碱起源于轴突而非施万细胞：神经切断 5 天后，刺激无释放反应。轴突中乙酰胆碱的释放与轴突终末的释放不同，因为其释放速率不能通过抑制钠钾 - 腺苷三磷酸酶（哇巴因 2×10⁻⁵ M）来增强，也不能被去甲肾上腺素（10⁻⁶ M）或吗啡调节。此外，尽管分离的神经干通过对 hemicholinium 敏感的过程摄取[³H]胆碱，但电刺激时无放射性释放。提示乙酰胆碱的释放并不局限于轴突终末，而是在有钙离子存在的情况下，轴突去极化可使其非突触性释放。
