Evidence for Functional Atypical Nicotinic Receptors That Activate K+-Dependent Cl- Secretion in Mouse Tracheal Epithelium
Evidence for Functional Atypical Nicotinic Receptors That Activate K+-Dependent Cl- Secretion in Mouse Tracheal Epithelium
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DOI：
10.1165/rcmb.2011-0171oc
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发表时间：
2012-01-01
影响因子：
6.4
通讯作者：
Fronius, Martin
中科院分区：
文献类型：
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作者：
Hollenhorst, Monika I.;Lips, Katrin S.;Fronius, Martin
本研究主要研究烟碱乙酰胆碱受体（nAChR）对小鼠气管上皮离子转运过程的影响。RT-PCR实验显示小鼠气管上皮中有α 3、α 4、α 5、α 7、α 9、α 10、β 2和β 4 nAChR亚基的表达。在小鼠气管的室内记录中，顶端施加尼古丁（100 μ M）可引起经上皮短路电流（EC50: 14.6 μ M）的剂量依赖性增加。甲美胺（25 μ M，根尖）和甲碱（1 μ M，根尖）可减弱烟碱诱导的效应。nAChR激动剂1.1-二甲基-4-苯基胡椒酸碘（DMPP） （100 μ M）显示了受体的顶端和基底外侧位置。I-NIC不受钠通道抑制剂阿米洛利（10 μ M，根尖）或囊性纤维化跨膜电导调节抑制剂CFTRinh-172 （20 μ M，根尖）的影响，但被氯通道抑制剂5-硝基-2-（3-苯丙胺）苯甲酸（100 μ M，根尖）、Na+/K+/2Cl（-）共转运蛋白抑制剂布美他尼（200 μ M，基侧）、钾通道抑制剂Ba2+（5mM，基侧）和4.4'-二异硫氰酸二苯乙烯-2.2'-二磺酸盐（100 μ M，根尖）降低。表明Ca2+激活的氯离子通道和钾离子通道的作用。去除细胞外Na+（根尖）或Ca2+（根尖）不影响I-NIC，但降低了DMPP的效果。Ca2+离子载体A23187, 3-异丁基-1-甲基黄嘌呤和forskolin的混合物，或肌醇-1,4,5-三磷酸（IP3）受体抑制剂2-氨基乙基二苯硼酸盐（75 mM，顶端）的实验降低了INIC，表明尼古丁介导的细胞内Ca2+和cAMP水平的增加涉及IP3信号通路。这些发现表明Ca2+渗透性nAChR的活性和通过nAChR激活介导气管上皮中Cl-和K+运输的替代代谢途径。
The present study focused on the influence of nicotinic acetylcholine receptors (nAChR) on ion transport processes in mouse tracheal epithelium. RT-PCR experiments revealed expression of the alpha 3, alpha 4, alpha 5, alpha 7, alpha 9, alpha 10, beta 2, and beta 4 nAChR subunits in mouse tracheal epithelium. In Ussing chamber recordings of mouse tracheae, apically applied nicotine (100 mu M) induced a dose-dependent increase of the transepithelial short-circuit current(EC50: 14.6 mu M). The nicotine-induced effect (I-NIC) was attenuated by mecamylamine (25 mu M, apical) and methyllycaconitine (1 mu M, apical). The nAChR agonist 1.1-dimethyl-4-phenylpiperatinium iodide (DMPP) (100 mu M) revealed apical and basolateral location of the receptors. I-NIC was not affected by the sodium channel inhibitor amiloride (10 mu M, apical) or the cystic fibrosis transmembrane conductance regulator inhibitor CFTRinh-172 (20 mu M, apical) but was reduced by the chloride channel inhibitor 5-nitro-2-(3-phenylpropylamino)benzoic acid (100 mu M, apical), the Na+/K+/2Cl(-) cotransporter inhibitor bumetanide (200 mu M, basolateral), the potassium channel inhibitor Ba2+(5mM, basolateral), and 4.4'-diisothiocyanatostilbene-2.2'-disulfonate (100 mu M, apical), indicating a contribution of Ca2+-activated chloride channels and potassium channels. Removal of extracellular Na+ (apical) or Ca2+ (apical) did not influence I-NIC but reduced the DMPP effect. Experiments with the Ca2+-ionophore A23187, a mix of 3-isobutyl-1-methylxanthine and forskolin, or the inositol-1,4,5-triphospate (IP3) receptor inhibitor 2-aminoethyldiphenyl-borinate (75 mM, apical) decreased INIC, indicating a nicotine-mediated increase of intracellular Ca2+ and cAMP levels involving the IP3 signaling pathway. These findings indicate the activity of Ca2+-permeable nAChRs and alternative metabotropic pathways by nAChR activation that mediate Cl- and K+ transport in tracheal epithelium.