Ballabeni V, Barocelli E, Chiavarini M, Bordi F, Impicciatore M
Institute of Pharmacology and Pharmacognosy, Faculty of Pharmacy, University of Parma.
Boll Soc Ital Biol Sper. 1992 Jul;68(7):437-44.
Among muscarinic agonists, the compound McN-A-343, originally proposed as selective stimulant of M1 cholinergic site, was subsequently questioned as a useful pharmacological tool in the classification of muscarinic receptors. In this work, evidence is presented for a dual response of McN-A-343 on longitudinal muscle-myenteric plexus preparation. On electrically-stimulated preparation, this agonist exhibited a pirenzepine-sensitive inhibition of the twitch contractions due to the involvement of neural M1-muscarinic receptor. On the other hand, a direct myogenic contractile action on the unstimulated tissue was observed using McN-A-343 in the same range of concentrations. This latter response, on the basis of the effects of muscarinic and non-muscarinic antagonists tested, seems to involve effectorial muscarinic sites with an unusual mechanism.
在毒蕈碱激动剂中，化合物McN-A-343最初被认为是M1胆碱能位点的选择性兴奋剂，后来却受到质疑，能否作为毒蕈碱受体分类的有效药理学工具。在这项研究中，有证据表明McN-A-343对纵行肌-肠肌丛标本有双重反应。在电刺激标本上，由于神经M1毒蕈碱受体的参与，该激动剂表现出对抽搐收缩的哌仑西平敏感抑制作用。另一方面，在相同浓度范围内使用McN-A-343时，观察到对未刺激组织有直接的肌源性收缩作用。基于所测试的毒蕈碱和非毒蕈碱拮抗剂作用，后一种反应似乎涉及效应性毒蕈碱位点，但其机制不同寻常。
