Isoflurane inhibits bronchopulmonary C-fiber-mediated apneic response to phenylbiguanide by depressing 5-HT₃ receptor function in anesthetized rats

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• 作者：Zhenxiong Zhang ; Jianguo Zhuang ; Cancan Zhang ; Fadi Xu
• 关键词：Volatile anesthetic ; 5-HT3 receptor ; Pulmonary sensory neurons ; Breathing
• 刊名：Neuroscience Letters
• 出版年：2013
• 出版时间：27 September, 2013
• 年：2013
• 卷：552
• 期：Complete
• 页码：1-4
• 全文大小：824 K

文摘

A previous study by the authors has shown that isoflurane (ISO), a commonly used volatile anesthetic, has an excitatory effect on bronchopulmonary C-fibers (PCFs). Since selective stimulation of PCFs by action on local 5-HT₃ receptors could evoke an apnea, this current study addresses whether inhalation of ISO would facilitate the PCF 5-HT₃ receptor-mediated apneic response and, if so, how. In anesthetized and spontaneously breathing rats, inhalation of 5 % ISO markedly inhibited the apneic response to intra-atrium injection of phenylbiguanide (PBG, 25 ¦Ìg/kg), a 5-HT₃ receptor agonist, which was contrary to the hypothesis. Extracellular recording of the nodose ganglion neurons in anesthetized, paralyzed and ventilated rats revealed that ISO attenuated the PBG-elicited excitation of pulmonary C neurons. Furthermore, using the patch clamp technique, it was found that ISO depressed the PBG-induced inward current of the pulmonary C neurons labeled with 1,1¡ä-dioctadecyl-3,3,3¡ä,3¡ä-tetramethylindocarbocyanine perchlorate (DiI) instilled previously into the lungs. These results suggest that ISO inhibits PCF 5-HT₃ channel functions, and thereby attenuates PCF excitatory response to PBG, likely contributing to the diminution of the PBG-induced apnea by ISO in rats.