Lu I-Jung, Ku Li-Chi, Lin Jin-Tun, Lee Kun-Ze, Hwang Ji-Chuu
Department of Biology, National Taiwan Normal University, Taipei, Taiwan, ROC.
Chin J Physiol. 2002 Dec 31;45(4):143-54.
The purpose of the current study was to characterize the response of the recurrent laryngeal nerve (RLN) to pulmonary C-fiber activation. Male rats of Wistar strain were anesthetized by urethane (1.2 g/kg, i.p.). Tracheostomy was performed. Catheter was inserted into the femoral artery and vein. Additional catheter was placed near the entrance of the right atrium via the right jugular vein. The animal was then paralyzed with gallamine triethiodide, ventilated and maintained at normocapnia in hyperoxia. Activities of the phrenic (PNA) and recurrent laryngeal nerves (RLNA) were monitored simultaneously. Two experimental protocols were completed. In the first experiment, various doses of capsaicin were delivered into the right atrium to activate pulmonary C-fibers with vagal intact. Low dose of capsaicin (1.25 microg/kg) produced apnea, a decrease in amplitude of PNA, an enhancement of RLNA during apnea and recovery from apnea, hypotension, and bradycardia. High dose of capsaicin (5 and 20 microg/kg) evoked the same tendency of response for both nerves and biphasic changes in blood pressure. Dose dependency was only seen in the period of apnea but not observable in nerve amplitudes. After bilateral vagotomy, low dose of capsaicin produced an increase in PNA without apnea, no significant change in RLNA, and hypertension. These results suggest that activation of vagal and nonvagal C-fibers could produce different reflex effects on cardiopulmonary functions. The reflex responses evoked by these two types of afferents might play defensive and protective roles in the airways and lungs.
本研究的目的是描述喉返神经（RLN）对肺C纤维激活的反应。选用雄性Wistar大鼠，用氨基甲酸乙酯（1.2 g/kg，腹腔注射）麻醉。行气管切开术。将导管插入股动脉和静脉。经右颈静脉在右心房入口附近放置另一根导管。然后用三碘季铵酚使动物麻痹，进行通气并维持在高氧状态下的正常碳酸血症。同时监测膈神经（PNA）和喉返神经（RLNA）的活动。完成了两个实验方案。在第一个实验中，将不同剂量的辣椒素注入右心房，在迷走神经完整的情况下激活肺C纤维。低剂量辣椒素（1.25 μg/kg）可导致呼吸暂停、膈神经动作电位幅度降低、呼吸暂停期间及呼吸暂停恢复时喉返神经活动增强、低血压和心动过缓。高剂量辣椒素（5和20 μg/kg）引起两条神经相同的反应趋势和血压的双相变化。剂量依赖性仅在呼吸暂停期可见，而在神经动作电位幅度上未观察到。双侧迷走神经切断术后，低剂量辣椒素可使膈神经活动增加但无呼吸暂停，喉返神经活动无明显变化，并出现高血压。这些结果表明，迷走神经和非迷走神经C纤维的激活可对心肺功能产生不同的反射效应。这两种传入神经引起的反射反应可能在气道和肺部起到防御和保护作用。
