Asano T, Ohta T, Otsuguro K, Ito S, Nakazato Y
Laboratory of Pharmacology, Hokkaido University, Sapporo, Japan.
J Vet Med Sci. 1995 Dec;57(6):1067-71. doi: 10.1292/jvms.57.1067.
Muscarinic receptor subtypes mediating catecholamine secretion and increase in the intracellular concentration of Ca2+ ([Ca2+]i) were examined using muscarinic agonists and antagonists in dispersed adrenal chromaffin cells of the guinea pig. All muscarinic agonists (1-1,000 microM) tested caused increases in adrenaline secretion in a dose-dependent manner. Muscarine and methacholine were more effective than bethanechol, oxotremorine and pilocarpine. Muscarine and oxotremorine caused a small increase in adrenaline secretion even in the absence of extracellular Ca2+. Both 4-DAMP (0.1 microM) and pirenzepine (0.1 microM), but not methoctramine (0.1 microM), shifted the dose-response curve for muscarine-induced adrenaline secretion to the right. These muscarinic agonists also caused increase in [Ca2+]i in the presence of extracellular Ca2+. Muscarine-induced [Ca2+]i rises were reduced, but not abolished, by removal of extracellular Ca2+. These results suggest that catecholamine secretion induced by muscarinic agonists is mediated through M1, or M1 and M3 muscarinic receptor subtypes in adrenal chromaffin cells of the guinea pig.
利用毒蕈碱激动剂和拮抗剂，在豚鼠分散的肾上腺嗜铬细胞中研究了介导儿茶酚胺分泌和细胞内钙离子浓度（[Ca2+]i）升高的毒蕈碱受体亚型。所有测试的毒蕈碱激动剂（1 - 1000微摩尔）均以剂量依赖方式引起肾上腺素分泌增加。毒蕈碱和乙酰甲胆碱比氨甲酰甲胆碱、氧化震颤素和毛果芸香碱更有效。即使在没有细胞外钙离子的情况下，毒蕈碱和氧化震颤素也会引起肾上腺素分泌少量增加。4 - DAMP（0.1微摩尔）和哌仑西平（0.1微摩尔）而非甲溴东莨菪碱（0.1微摩尔）将毒蕈碱诱导的肾上腺素分泌剂量反应曲线右移。这些毒蕈碱激动剂在有细胞外钙离子存在时也会引起[Ca2+]i升高。去除细胞外钙离子可使毒蕈碱诱导的[Ca2+]i升高降低，但并未消除。这些结果表明，毒蕈碱激动剂诱导的儿茶酚胺分泌是通过豚鼠肾上腺嗜铬细胞中的M1或M1和M3毒蕈碱受体亚型介导的。
