Kilbinger H, Nafziger M
Naunyn Schmiedebergs Arch Pharmacol. 1985 Jan;328(3):304-9. doi: 10.1007/BF00515558.
Longitudinal muscle strips of the guinea-pig ileum were incubated with [3H]choline and the effects of muscarinic agonists on smooth muscle contraction and on spontaneous and electrically-evoked outflow of tritium were studied. Muscarine and pilocarpine concentration-dependently increased both muscle contraction and spontaneous outflow of [3H]ACh, and inhibited the electrically-evoked outflow of [3H]ACh. The increase in spontaneous outflow was prevented by tetrodotoxin and scopolamine, but not by hexamethonium. Oxotremorine (1-100 microM) did not increase the spontaneous outflow of tritium. Pirenzepine in concentrations of 10 and 100 nM hardly affected the muscle contractions induced by pilocarpine, but significantly antagonized the pilocarpine-evoked increases in [3H]ACh outflow. Likewise, pirenzepine (100 nM) antagonized more effectively the enhancement by muscarine of spontaneous outflow than the inhibitory effect of muscarine on the electrically-evoked release of [3H]ACh. Scopolamine (1 and 10 nM) antagonized to a similar extent the effects of pilocarpine on spontaneous outflow of [3H]ACh and on muscle contraction. The results suggest that the cholinergic nerves of the myenteric plexus are endowed with excitatory (ganglionic) and inhibitory (prejunctional) muscarine receptors which modulate the release of ACh and which differ in their affinities to pirenzepine.
将豚鼠回肠的纵行肌条与[3H]胆碱一起孵育，研究了毒蕈碱激动剂对平滑肌收缩以及对氚的自发和电诱发流出的影响。毒蕈碱和毛果芸香碱浓度依赖性地增加了肌肉收缩和[3H]乙酰胆碱的自发流出，并抑制了[3H]乙酰胆碱的电诱发流出。河豚毒素和东莨菪碱可阻止自发流出的增加，但六甲铵不能。氧化震颤素（1 - 100 microM）不会增加氚的自发流出。10和100 nM浓度的哌仑西平几乎不影响毛果芸香碱诱导的肌肉收缩，但能显著拮抗毛果芸香碱诱发的[3H]乙酰胆碱流出增加。同样，哌仑西平（100 nM）拮抗毒蕈碱对自发流出增强作用比其对[3H]乙酰胆碱电诱发释放的抑制作用更有效。东莨菪碱（1和10 nM）对毛果芸香碱对[3H]乙酰胆碱自发流出和肌肉收缩的影响具有相似程度的拮抗作用。结果表明，肌间神经丛的胆碱能神经具有兴奋性（神经节）和抑制性（节前）毒蕈碱受体，它们调节乙酰胆碱的释放，并且对哌仑西平的亲和力不同。
