Tangsucharit Panot, Takatori Shingo, Zamami Yoshito, Goda Mitsuhiro, Pakdeechote Poungrat, Kawasaki Hiromu, Takayama Fusako
Department of Clinical Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan; Department of Pharmacology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
Department of Clinical Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan; Department of Clinical Pharmacy, College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime, Japan.
J Pharmacol Sci. 2016 Jan;130(1):24-32. doi: 10.1016/j.jphs.2015.12.005. Epub 2016 Jan 8.
The present study investigated pharmacological characterizations of muscarinic acetylcholine receptor (AChR) subtypes involving ACh-induced endothelium-independent vasodilatation in rat mesenteric arteries. Changes in perfusion pressure to periarterial nerve stimulation and ACh were measured before and after the perfusion of Krebs solution containing muscarinic receptor antagonists. Distributions of muscarinic AChR subtypes in mesenteric arteries with an intact endothelium were studied using Western blotting. The expression level of M1 and M3 was significantly greater than that of M2. Endothelium removal significantly decreased expression levels of M2 and M3, but not M1. In perfused mesenteric vascular beds with intact endothelium and active tone, exogenous ACh (1, 10, and 100 nmol) produced concentration-dependent and long-lasting vasodilatations. In endothelium-denuded preparations, relaxation to ACh (1 nmol) disappeared, but ACh at 10 and 100 nmol caused long-lasting vasodilatations, which were markedly blocked by the treatment of pirenzepine (M1 antagonist) or 4-DAMP (M1 and M3 antagonist) plus hexamethonium (nicotinic AChR antagonist), but not methoctramine (M2 and M4 antagonist). These results suggest that muscarinic AChR subtypes, mainly M1, distribute throughout the rat mesenteric arteries, and that activation of M1 and/or M3 which may be located on CGRPergic nerves releases CGRP, causing an endothelium-independent vasodilatation.
本研究调查了毒蕈碱型乙酰胆碱受体（AChR）亚型在大鼠肠系膜动脉中参与乙酰胆碱诱导的非内皮依赖性血管舒张的药理学特性。在灌注含毒蕈碱受体拮抗剂的 Krebs 溶液前后，测量了对动脉周围神经刺激和乙酰胆碱的灌注压力变化。使用蛋白质印迹法研究了完整内皮的肠系膜动脉中毒蕈碱型 AChR 亚型的分布。M1 和 M3 的表达水平显著高于 M2。去除内皮显著降低了 M2 和 M3 的表达水平，但不影响 M1。在具有完整内皮和活性张力的灌注肠系膜血管床中，外源性乙酰胆碱（1、10 和 100 nmol）产生浓度依赖性和持久的血管舒张。在去内皮的制剂中，对 1 nmol 乙酰胆碱的舒张反应消失，但 10 和 100 nmol 的乙酰胆碱引起持久的血管舒张，这被哌仑西平（M1 拮抗剂）或 4-DAMP（M1 和 M3 拮抗剂）加六甲铵（烟碱型 AChR 拮抗剂）处理显著阻断，但不受甲溴东莨菪碱（M2 和 M4 拮抗剂）影响。这些结果表明，毒蕈碱型 AChR 亚型，主要是 M1，分布于整个大鼠肠系膜动脉，并且位于降钙素基因相关肽能神经上的 M1 和/或 M3 的激活释放降钙素基因相关肽，导致非内皮依赖性血管舒张。
