Maclagan J, Barnes P J
Trends Pharmacol Sci. 1989 Dec;Suppl:88-92.
Muscarinic receptors have been identified in the airways in several species, including humans, located on airway smooth muscle, secreting cells and on the nerves. M1 receptors are found in sympathetic ganglia in the guinea-pig and in parasympathetic ganglia in humans. M2 receptors (inhibitory autoreceptors) are found in cholinergic parasympathetic nerve terminals in many species, including humans, whereas the muscarinic receptors found on airway smooth muscle and mucus glands belong to the M3 subtype. It is possible that a defect in neuronal M2 receptor function may explain beta-blocker-induced asthma. M2 antagonists such as methoctramine are promising tools for elucidating the role of muscarinic receptor subtypes in the lung. However, they can potentially increase acetylcholine release. This property is not shown by drugs with a higher selectivity for M1 and M3 receptors which are likely to be useful clinically in the treatment of airway disease.
在包括人类在内的多个物种的气道中已鉴定出毒蕈碱受体，它们位于气道平滑肌、分泌细胞和神经上。M1受体存在于豚鼠的交感神经节和人类的副交感神经节中。M2受体（抑制性自身受体）在包括人类在内的许多物种的胆碱能副交感神经末梢中都有发现，而气道平滑肌和黏液腺上发现的毒蕈碱受体属于M3亚型。神经元M2受体功能缺陷可能是β受体阻滞剂诱发哮喘的原因。像甲溴东莨菪碱这样的M2拮抗剂是阐明毒蕈碱受体亚型在肺部作用的有前景的工具。然而，它们可能会增加乙酰胆碱的释放。对M1和M3受体具有更高选择性的药物则不会表现出这种特性，这些药物在临床上可能对治疗气道疾病有用。
