Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan.
Department of Otolaryngology, University of Tokyo, Tokyo, 113-8655, Japan.
J Physiol. 2019 Jun;597(11):2949-2963. doi: 10.1113/JP277895. Epub 2019 May 8.
Afferents carried by the superior laryngeal nerve play a primary role in the initiation of laryngeal mechanically evoked swallows in anaesthetized rats. Amiloride and its analogues inhibit swallowing evoked by mechanical stimulation, but not swallowing evoked by chemical and electrical stimulation. The epithelial sodium channel is probably involved in the initiation of laryngeal mechanically evoked swallows.
The swallowing reflex plays a critical role in airway protection. Because impaired laryngeal mechanosensation is associated with food bolus aspiration, it is important to know how the laryngeal sensory system regulates swallowing initiation. This study was performed to clarify the neuronal mechanism of mechanically evoked swallows. Urethane-anaesthetized Sprague-Dawley male rats were used. A swallow was identified by activation of the suprahyoid and thyrohyoid muscles on electromyography. The swallowing threshold was measured by von Frey filament and electrical stimulation of the larynx. The number of swallows induced by upper airway distension and capsaicin application (0.03 nmol, 3 μl) to the vocal folds was counted. The effects of topical application (0.3-30 nmol, 3 μl) of the epithelial sodium channel (ENaC) blocker amiloride and its analogues (benzamil and dimethylamiloride), acid-sensing ion channel (ASIC) inhibitors (mambalgine-1 and diminazene) and gadolinium to the laryngeal mucosa on swallowing initiation were evaluated. A nerve transection study indicated that afferents carried by the superior laryngeal nerve play a primary role in the initiation of laryngeal mechanically evoked swallows. The mechanical threshold of swallowing was increased in a dose-dependent manner by amiloride and its analogues and gadolinium, but not by ASIC inhibitors. The number of swallows by upper airway distension was significantly decreased by benzamil application. However, the initiation of swallows evoked by capsaicin and electrical stimulation was not affected by benzamil application. We speculate that the ENaC is involved in the initiation of laryngeal mechanically evoked swallows.
由喉上神经携带的传入神经在麻醉大鼠的喉机械诱发吞咽中起主要作用。阿米洛利及其类似物抑制机械刺激诱发的吞咽，但不抑制化学和电刺激诱发的吞咽。上皮钠离子通道可能参与了喉机械诱发吞咽的启动。
吞咽反射在气道保护中起着至关重要的作用。由于喉感觉功能障碍与食物团块吸入有关，因此了解喉感觉系统如何调节吞咽的启动非常重要。本研究旨在阐明机械诱发吞咽的神经机制。使用乌拉坦麻醉的 Sprague-Dawley 雄性大鼠。通过肌电图激活舌骨上肌和舌骨下肌来识别吞咽。通过 von Frey 细丝和喉电刺激测量吞咽阈值。计数上气道扩张和辣椒素（0.03 nmol，3 μl）应用于声带时诱发的吞咽次数。评估上皮钠离子通道（ENaC）阻断剂阿米洛利及其类似物（苯甲脒和二甲基阿米洛利）、酸感应离子通道（ASIC）抑制剂（mambalgine-1 和地美硝唑）和镧在喉黏膜上的局部应用（0.3-30 nmol，3 μl）对吞咽启动的影响。神经切断研究表明，由喉上神经携带的传入神经在喉机械诱发吞咽的启动中起主要作用。阿米洛利及其类似物和镧以剂量依赖的方式增加吞咽的机械阈值，但不增加 ASIC 抑制剂的机械阈值。苯甲脒应用可显著减少由上气道扩张引起的吞咽次数。然而，苯甲脒应用并不影响辣椒素和电刺激诱发的吞咽启动。我们推测 ENaC 参与了喉机械诱发吞咽的启动。
