Distribution and types of adrenoceptors in the guinea-pig ileum: the action of alpha- and beta-adrenoceptor blocking agents.
Distribution and types of adrenoceptors in the guinea-pig ileum: the action of alpha- and beta-adrenoceptor blocking agents.
复制标题
豚鼠回肠中肾上腺素受体的分布和类型：α-和β-肾上腺素受体阻断剂的作用。
DOI：
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发表时间：
1982
影响因子：
7.3
通讯作者：
V. Bauer
中科院分区：
文献类型：
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作者：
V. Bauer
1用跨壁刺激豚鼠回肠，分析回肠末端(0~3 cm)和回盲部近端(距回盲瓣50 cm)不同的肾上腺素能受体。研究了位于末梢、胆碱能、运动神经末梢的突触前肾上腺素受体(位于终末、胆碱能、运动神经末梢上)和连接后肾上腺素受体(位于肌膜上)对α、β激动剂和拮抗剂的敏感性。4肾上腺素能受体激动剂(去甲肾上腺素、肾上腺素和麻黄碱)的收缩抑制作用不被酚苄明(0.1、0.5和1um)、卡比丁(0.5、1和5um)和心得安(0.5、1和5um)所拮抗；酚妥拉明(0.1、0.5、1.25和5微米)和育亨宾(0.25、0.5和5微米)均能抑制去甲肾上腺素和肾上腺素引起的回肠末端收缩和回肠末端和回肠近端由去甲肾上腺素和肾上腺素引起的收缩，苯妥拉明、卡比丁和酚妥拉明均能拮抗去甲肾上腺素和肾上腺素引起的回肠收缩，而育亨宾和心得安则不影响这些激动剂。引起乙酰胆碱引起的回肠近端和末端持续收缩的松弛。心得安可拮抗异丙肾上腺素的松弛作用，育亨宾可拮抗去甲肾上腺素和麻黄碱的作用。结果表明，豚鼠回肠存在突触后β受体和至少两种类型的α受体：α(1)-兴奋性交感后肾上腺素受体，可被去甲肾上腺素、去甲肾上腺素和肾上腺素激活，并被苯氧苯甲胺、卡比丁和酚妥拉明拮抗；α(2)-抑制性交感前肾上腺素受体，由麻黄碱、去甲肾上腺素和肾上腺素激活，并被去甲肾上腺素和酚妥拉明拮抗。节后抑制性α-肾上腺素受体更接近于α(2)-肾上腺素受体，因为它们主要受麻黄素和去甲肾上腺素的刺激，而被育亨宾抑制。9已经证明，所有的α-肾上腺素受体亚型都可以在离回盲瓣每隔一段距离(0到70厘米)处被发现，它们可以在静息状态或乙酰胆碱收缩状态下被激活。
1 Transmurally stimulated segments of the guinea-pig ileum have been used to analyse the different adrenoceptors in the terminal (0 to 3 cm) and the proximal (> 50 cm from the ileocaecal valve) ileum.2 The prejunctional adrenoceptors (located on the final, cholinergic, motor nerve terminals) and postjunctional adrenoceptors (located on the smooth muscle membrane) have been characterized according to their sensitivity to alpha- and beta-agonists and antagonists.3 Phentolamine, phenoxybenzamine and yohimbine, in concentrations of 0.1 muM, transiently enhanced (up to 10%) the twitch response. At higher concentrations all the alpha- and beta-antagonists studied depressed the neurogenic twitches and relaxed the smooth muscle.4 The twitch-inhibitory effects of adrenoceptor agonists (noradrenaline, adrenaline and ephedrine) were not antagonized by phenoxybenzamine (0.1, 0.5 and 1 muM), carbidine (0.5, 1 and 5 muM) and propranolol (0.5, 1 and 5 muM); however, they were depressed by phentolamine (0.1, 0.5, 1.25 and 5 muM) and yohimbine (0.25, 0.5 and 5 muM).5 The smooth muscle contractions induced by noradrenaline and adrenaline in the terminal ileum and by phenylephrine in both the terminal and proximal ileum were antagonized by phenoxybenzamine, carbidine and phentolamine but were not influenced by yohimbine and propranolol.6 The smooth muscle relaxations of the proximal ileum induced by noradrenaline, adrenaline and ephedrine were inhibited by yohimbine, phentolamine, carbidine and phenoxybenzamine, and the isoprenaline-induced relaxation was antagonized by propranolol.7 All the agonists studied, except phenylephrine, elicited relaxations of the acetylcholine-induced sustained contraction of both proximal and terminal ileum. The relaxation induced by isoprenaline was antagonized by propranolol, and the effects of noradrenaline and ephedrine by yohimbine.8 It is concluded that in the guinea-pig ileum there are postsynaptic beta-adrenoceptors and at least two types of alpha-adrenoceptors: alpha(1)-excitatory postjunctional adrenoceptors activated by phenylephrine, noradrenaline and adrenaline and antagonized by phenoxybenzamine, carbidine and phentolamine; alpha(2)-inhibitory prejunctional adrenoceptors activated by ephedrine, noradrenaline and adrenaline and inhibited by yohimbine and phentolamine. The inhibitory postjunctional alpha-adrenoceptors are more close to the alpha(2)-adrenoceptors, since they were stimulated predominantly by ephedrine and noradrenaline and inhibited by yohimbine.9 It has been shown that all alpha-adrenoceptor subtypes are to be found at every distance (0 to 70 cm) from the ileocaecal valve and that they can be activated in the resting or in the acetylcholine-contracted states.