查看Ch14 The Autonomic Nervous System的源代码

=== 所有节前神经元（包括交感神经和副交感神经）都会释放乙酰胆碱并刺激节后神经元上的 N2 烟碱受体 ===
<b style=color:#0ae>All preganglionic neurons—both sympathetic and parasympathetic—release acetylcholine and stimulate N2 nicotinic receptors on postganglionic neurons</b>

At synapses between postganglionic neurons and target cells, the two major divisions of the ANS use different neurotransmitters and receptors (Table 14-1). However, in both the sympathetic and parasympathetic divisions, synaptic transmission between preganglionic and postganglionic neurons (termed ganglionic transmission because the synapse is located in a ganglion) is mediated by acetylcholine (ACh) acting on nicotinic receptors (Fig. 14-8). Nicotinic receptors are ligand-gated channels (i.e., ionotropic receptors) with a pentameric structure (see pp. 212–213). Table 14-2 summarizes some of the properties of nicotinic receptors. The nicotinic receptors on postganglionic autonomic neurons are of a molecular subtype (N2) different from that found at the neuromuscular junction (N1). Both are ligand-gated ion channels activated by ACh or nicotine. However, whereas the N1 receptors at the neuromuscular junction (see p. 212) are stimulated by decamethonium and preferentially blocked by d-tubocurarine, N8-2 the autonomic N2 receptors are stimulated by tetramethylammonium but resistant to d-tubocurarine. When activated, N1 and N2 receptors are both permeable to Na+ and K+. Thus, nicotinic transmission triggered by stimulation of preganglionic neurons leads to rapid depolarization of postganglionic neurons.

在节后神经元和靶细胞之间的突触处，ANS 的两个主要分支使用不同的神经递质和受体（表 14-1）。然而，在交感神经和副交感神经分支中，节前神经元和节后神经元之间的突触传递（称为神经节传递，因为突触位于神经节中）是由作用于烟碱受体的乙酰胆碱 （ACh） 介导的（图 14-8）。烟碱受体是具有五聚体结构的配体门控通道（即离子型受体）（参见第 212-213 页）。表 14-2 总结了烟碱受体的一些特性。节后自主神经神经元上的烟碱受体属于与神经肌肉接头 （N1） 处发现的分子亚型 （N2） 不同。两者都是由 ACh 或尼古丁激活的配体门控离子通道。然而，神经肌肉接头处的 N1 受体（见第 212 页）受十甲铵刺激并优先被 d-tubocurarine 阻断，而自主神经 N2 受体受四甲基铵刺激，但对 d-tubocurarine 耐药。激活后，N1 和 N2 受体均能渗透 Na+ 和 K+。因此，由节前神经元刺激触发的烟碱传递导致节后神经元的快速去极化。

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