Effect of tetrodotoxin on cholinergic agonist-mediated colonic electrolyte transport.
Effect of tetrodotoxin on cholinergic agonist-mediated colonic electrolyte transport.
复制标题
河豚毒素对胆碱能激动剂介导的结肠电解质转运的影响。
DOI：
10.1152/ajpgi.1983.244.4.g386
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Binder,HJ
中科院分区：
文献类型：
--
作者：
Zimmerman,TW;Binder,HJ
毒蕈碱胆碱能激动剂刺激肠内电解质分泌;烟碱激动剂增加吸收。最近的研究表明，在兔回肠烟碱，而不是毒蕈碱激动剂通过中介神经递质。这些在大鼠结肠的体外研究，以确定是否河豚毒素（TTX），一种有效的神经毒素，抑制胆碱能激动剂诱导的电解质转运的变化。TTX并没有显着改变基础离子转运或离子转运的变化所产生的茶碱或bethanechol，毒蕈碱激动剂。在浓度为1 mM的卡巴胆碱（一种混合的毒蕈碱-烟碱激动剂）下，对离子转运没有明显影响，但在TTX存在下，净钠吸收显著降低，与单独使用1 μ M卡巴胆碱产生的效果相似。这些结果是一致的概念，即在低浓度卡巴胆碱主要作为一个毒蕈碱激动剂;在高浓度卡巴胆碱表现出毒蕈碱和烟碱的性质是等同的。我们的结论是，毒蕈碱激动剂改变电解质转运直接作用于肠上皮细胞和烟碱激动剂间接作用于刺激释放的中间神经递质。
Muscarinic cholinergic agonists stimulate electrolyte secretion in the intestine; nicotinic agonists augment absorption. Recent studies in rabbit ileum suggest that nicotinic but not muscarinic agonists act via an intermediary neurotransmitter. These in vitro studies in rat colon were performed to determine whether tetrodotoxin (TTX), a potent neurotoxin, inhibits cholinergic agonist-induced changes in electrolyte transport. TTX did not significantly alter basal ion transport or the ion transport changes produced by either theophylline or bethanechol, a muscarinic agonist. At a concentration of 1 mM carbachol, a mixed muscarinic-nicotinic agonist, had no apparent effect on ion transport but in the presence of TTX significantly decreased net sodium absorption, similar to the effect produced by 1 microM carbachol alone. These results are consistent with the concept that in low concentrations carbachol acts predominantly as a muscarinic agonist; in high concentrations carbachol exhibits both muscarinic and nicotinic properties that are equivalent. We conclude that muscarinic agonists alter electrolyte transport by acting directly on the enterocyte and that nicotinic agonists act indirectly by stimulating the release of an intermediary neurotransmitter.