Yang B, McCaffrey T V
Department of Physiology and Biophysics, Mayo Clinic, Rochester, Minnesota, USA.
Rhinology. 1996 Sep;34(3):136-9.
Muscarinic receptors are believed to play an important role in modulation of ciliary action in respiratory system. We studied the in vitro effect of methacholine, a beta-methyl ester of acetylcholine, on the ciliary beat frequency (CBF). Adenoid explants were cultured in Minimum Essential Medium Eagle (MEM). CBF was determined using microphotometry. Methacholine (10(-6) M) increased CBF a maximum of 10.34 +/- 0.42% (p < 0.001). The non-selective muscarinic antagonist atropine (10(-6) M) significantly inhibited the ciliostimulatory effects of methacholine (p < 0.001). To characterize the muscarinic receptor subtypes in nasal mucosa, the selective M1-, M2- and M3-muscarinic antagonists pirenzepine dihydrochloride (PZ), gallamine triethiodide (gallamine), and 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) were used prior to addition of methacholine, PZ and 4-DAMP, at concentrations of 10(-6) to 10(-8) M, significantly inhibited the ciliostimulatory effects of methacholine (p < 0.0001). There was no significant inhibition of methacholine-induced ciliostimulation by gallamine (p > 0.3). Our study showed that ciliostimulation by methacholine in human upper airway mucosa involves M1- and M3- muscarinic receptor subtypes, but not the M2-receptor subtype. The identification of the muscarinic receptor subtypes and intracellular signalling mechanisms involved in CBF modulation will permit the selection appropriate of pharmacological agents for treating the cholinergic symptoms of rhinitis.
毒蕈碱受体被认为在调节呼吸系统纤毛运动中起重要作用。我们研究了乙酰胆碱的β-甲酯——乙酰甲胆碱对纤毛摆动频率（CBF）的体外作用。腺样体组织块在伊格尔氏最低限度基本培养基（MEM）中培养。使用显微光度测定法测定CBF。乙酰甲胆碱（10⁻⁶ M）使CBF最大增加10.34±0.42%（p<0.001）。非选择性毒蕈碱拮抗剂阿托品（10⁻⁶ M）显著抑制了乙酰甲胆碱的纤毛刺激作用（p<0.001）。为了鉴定鼻黏膜中的毒蕈碱受体亚型，在加入乙酰甲胆碱之前使用了选择性M1、M2和M3毒蕈碱拮抗剂盐酸哌仑西平（PZ）、三碘季铵酚（加拉明）和4-二苯基乙酰氧基-N-甲基哌啶甲碘化物（4-DAMP），浓度为10⁻⁶至10⁻⁸ M的PZ和4-DAMP显著抑制了乙酰甲胆碱的纤毛刺激作用（p<0.0001）。加拉明对乙酰甲胆碱诱导的纤毛刺激没有显著抑制作用（p>0.3）。我们的研究表明，乙酰甲胆碱对人上呼吸道黏膜的纤毛刺激涉及M1和M3毒蕈碱受体亚型，而不涉及M2受体亚型。鉴定参与CBF调节的毒蕈碱受体亚型和细胞内信号传导机制将有助于选择合适的药物来治疗鼻炎的胆碱能症状。
