Bauer V, Kuriyama H
Br J Pharmacol. 1982 Aug;76(4):603-11. doi: 10.1111/j.1476-5381.1982.tb09260.x.
1 The effects of adrenoceptor agonists and antagonists on spontaneous and evoked membrane activities of longitudinal muscle cells from different parts of the guinea-pig ileum were observed, using microelectrode methods.2 Isoprenaline inhibited the generation of spikes in cells in the terminal (0-3 cm from the ileocaecal valve) and proximal (more than 50 cm from the ileocaecal valve) regions of the ileum, with no change on the membrane potential and ionic conductance of the membrane. These actions of isoprenaline were abolished by propranolol.3 Noradrenaline and phenylephrine depolarized the membrane and increased both the spike frequency and ionic conductance of cell membranes of the terminal ileum, whereas noradrenaline and clonidine hyperpolarized the membrane, increased the ionic conductance of the membrane and inhibited the spontaneously generated spikes from cells of the proximal ileum. The excitatory effect of phenylephrine in the cells of the proximal ileum and the inhibitory effect of clonidine on cells of the terminal ileum were less pronounced.4 The excitatory actions of noradrenaline or phenylephrine were antagonized by prazosin and phentolamine, but not by yohimbine, whereas the inhibitory actions of noradrenaline or clonidine were antagonized by yohimbine and phentolamine but not by prazosin.5 The cholinergic e.j.ps evoked by field stimulation to the tissue were not affected by isoprenaline or phenyleprine but were inhibited by noradrenaline and clonidine, in both the terminal and proximal regions of the ileum. These actions of noradrenaline and clonidine were antagonized by yohimbine but not by prazosin.6 The results indicate that in the myenteric plexus and longitudinal muscle tissues of the guinea-pig ileum there are prejunctional inhibitory (alpha(2)), postjunctional inhibitory (alpha(2) and beta) and postjunctional excitatory (alpha(1)) adrenoceptors. The homogeneous distributions of prejunctional alpha(2)- and postjunctional beta-adrenoceptors in the ileum are responsible for inhibitions of cholinergic excitatory junction potentials (e.j.ps) and spontaneous spike activities, respectively. The density of distribution of the postjunctional alpha(1)-adrenoceptors is higher in the terminal than in the proximal regions, and these distributions are reversed in the case of the postjunctional alpha(2)-adrenoceptors. The postjunctional alpha(1)-adrenoceptors are probably responsible for the membrane depolarization and alpha(2)-adrenoceptors for the hyperpolarization induced by catecholamines.
采用微电极方法，观察了肾上腺素能受体激动剂和拮抗剂对豚鼠回肠不同部位纵行肌细胞自发和诱发膜活动的影响。
异丙肾上腺素抑制回肠末端（距回盲瓣0 - 3厘米）和近端（距回盲瓣超过50厘米）区域细胞的锋电位产生，而对膜电位和膜离子电导无影响。普萘洛尔可消除异丙肾上腺素的这些作用。
去甲肾上腺素和苯肾上腺素使回肠末端细胞膜去极化，增加锋电位频率和细胞膜离子电导，而去甲肾上腺素和可乐定使细胞膜超极化，增加膜离子电导并抑制回肠近端细胞的自发锋电位。苯肾上腺素对回肠近端细胞的兴奋作用和可乐定对回肠末端细胞的抑制作用不太明显。
去甲肾上腺素或苯肾上腺素的兴奋作用可被哌唑嗪和酚妥拉明拮抗，但不能被育亨宾拮抗，而去甲肾上腺素或可乐定的抑制作用可被育亨宾和酚妥拉明拮抗，但不能被哌唑嗪拮抗。
对组织进行场刺激诱发的胆碱能兴奋性接头电位（e.j.ps）不受异丙肾上腺素或苯肾上腺素影响，但在回肠末端和近端区域均被去甲肾上腺素和可乐定抑制。去甲肾上腺素和可乐定的这些作用可被育亨宾拮抗，但不能被哌唑嗪拮抗。
结果表明，在豚鼠回肠的肌间神经丛和纵行肌组织中存在节前抑制性（α₂）、节后抑制性（α₂和β）和节后兴奋性（α₁）肾上腺素能受体。回肠中节前α₂ - 肾上腺素能受体和节后β - 肾上腺素能受体的均匀分布分别导致胆碱能兴奋性接头电位（e.j.ps）和自发锋电位活动受到抑制。节后α₁ - 肾上腺素能受体的分布密度在末端高于近端区域，而节后α₂ - 肾上腺素能受体的分布情况则相反。节后α₁ - 肾上腺素能受体可能是儿茶酚胺诱导膜去极化的原因，而α₂ - 肾上腺素能受体则是超极化的原因。
