Airway Hyperresponsiveness Induced by Repeated Esophageal Infusion of HCl in Guinea Pigs
Airway Hyperresponsiveness Induced by Repeated Esophageal Infusion of HCl in Guinea Pigs
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DOI：
10.1165/rcmb.2013-0484oc
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发表时间：
2014-11-01
影响因子：
6.4
通讯作者：
Wu, Da-Zheng
中科院分区：
文献类型：
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作者：
Cheng, Yan-Mei;Cao, Ai-Li;Wu, Da-Zheng
胃食管反流是一种常见病，与慢性咳嗽、哮喘、慢性支气管炎、慢性阻塞性疾病等慢性气道疾病密切相关。的确，胃食管酸反流进入呼吸道引起支气管收缩，但其潜在机制仍未明确。本研究旨在阐明胃食管反流动物模型中豚鼠支气管平滑肌（BSMs）的功能变化。经食管HCl输注14天后，观察到豚鼠明显的气道炎症、高反应性和重塑。此外，与对照组相比，注入HCl的豚鼠对乙酰胆碱（ACh）、KCl、电场刺激和细胞外Ca2+的收缩反应更大。l型电压依赖性Ca2+通道（L-VDCC）阻滞剂尼卡地平显著抑制HCl输注豚鼠ACh-和Ca2+增强的BSM收缩。rho激酶抑制剂Y27632可减弱HCl输注豚鼠乙酰胆碱增强的BSM收缩。采用实时荧光定量PCR和Western blot检测BSM中毒蕈碱M-2和M-3受体、RhoA和L-VDCC mRNA和蛋白的表达。毒蕈碱M3受体、RhoA和L-VDCC mRNA和蛋白的表达高于hcl输注豚鼠BSM，而毒蕈碱M2受体水平不变。我们证明，在豚鼠中，酸输注到食管下部，随后微吸到呼吸道会导致气道高反应性和过度活跃的BSM。功能和分子结果表明，过度活跃的BSM是通过L-VDCC增强细胞外Ca2+内流和通过rho激酶信号通路增强Ca2+敏化的原因。
Gastroesophageal reflux is a common disorder closely related to chronic airway diseases, such as chronic cough, asthma, chronic bronchitis, and chronic obstructive disease. Indeed, gastroesophageal acid reflux into the respiratory tract causes bronchoconstriction, but the underlying mechanisms have still not been clarified. This study aimed to elucidate functional changes of bronchial smooth muscles (BSMs) isolated from guinea pigs in an animal model of gastroesophageal reflux. The marked airway inflammation, hyperresponsiveness and remodeling were observed after guinea pigs were exposed to intraesophageal HCl infusion for 14 days. In addition, contractile responses to acetylcholine (ACh), KCl, electrical field stimulation, and extracellular Ca2+ were greater in guinea pigs infused with HCl compared with control groups. The L-type voltage-dependent Ca2+ channels (L-VDCC) blocker, nicardipine, significantly inhibited ACh- and Ca2+-enhanced BSM contractions in guinea pigs infused with HCl. The Rho-kinase inhibitor, Y27632, attenuated ACh-enhanced BSM contractions in guinea pigs infused with HCl. Moreover, mRNA and protein expressions for muscarinic M-2 and M-3 receptors, RhoA, and L-VDCC in BSM were detected by real-time PCR and Western blot. Expressions of mRNA and protein for muscarinic M3 receptors, RhoA, and L-VDCC were greater than in BSM of HCl-infused guinea pigs, whereas levels of muscarinic M2 receptors were unchanged. We demonstrate that acid infusion to the lower esophagus and, subsequently, microaspiration into the respiratory tract in guinea pigs leads to airway hyperresponsiveness and overactive BSM. Functional and molecular results indicate that overactive BSM is the reason for enhancement of extracellular Ca2+ influx via L-VDCC and Ca2+ sensitization through Rho-kinase signaling.