Ravi K, Singh M
Department of Physiology, V.P. Chest Institute, University of Delhi, India.
Respir Physiol. 1996 Nov;106(2):137-51. doi: 10.1016/s0034-5687(96)00070-9.
Apnoea, bradycardia and hypotension were elicited by right atrial injections of capsaicin in anaesthetized monkeys. At the threshold dose (2.5 +/- 0.3 microgram/kg), tachypnoea was elicited (latency 1.6 +/- 0.2 s) which got replaced by apnoea with higher doses of capsaicin. These responses persisted (1) after cooling the cervical vagi to 6-8 degrees C, and (2) after instilling xylocaine into the pericardial sac. Tachypnoea and apnoea were elicited after bilateral cervical vagotomy also, but only with higher doses and after a longer latency (5.0 +/- 0.3 s). Right atrial injection of capsaicin and insufflation of halothane stimulated vagal pulmonary C-fibre receptors with a latency of 1.7 +/- 0.7 s and 0.2 +/- 0.1 s, respectively. Tachypnoea/apnoea, bradycardia and hypotension were elicited by left atrial injection of capsaicin also (threshold dose: 5.0 +/- 1.2 micrograms/kg). The respiratory responses persisted (1) after instilling xylocaine into the pericardial sac, and (2) after bilateral cervical vagotomy suggesting that they were due to stimulation of non-cardiac receptors with sympathetic afferents. It is concluded that the initial respiratory responses elicited by right atrial injection of capsaicin were due to stimulation of pulmonary C-fibre receptors with vagal afferents.
在麻醉的猴子中，通过右心房注射辣椒素诱发呼吸暂停、心动过缓和低血压。在阈剂量（2.5±0.3微克/千克）时，诱发呼吸急促（潜伏期1.6±0.2秒），随着辣椒素剂量增加，呼吸急促被呼吸暂停所取代。这些反应在以下情况下持续存在：（1）将颈迷走神经冷却至6-8摄氏度后；（2）在心包囊内注入利多卡因后。双侧颈迷走神经切断术后也会诱发呼吸急促和呼吸暂停，但仅在更高剂量且潜伏期更长（5.0±0.3秒）时出现。右心房注射辣椒素和氟烷吹入分别以1.7±0.7秒和0.2±0.1秒的潜伏期刺激迷走神经肺C纤维受体。左心房注射辣椒素也会诱发呼吸急促/呼吸暂停、心动过缓和低血压（阈剂量：5.0±1.2微克/千克）。呼吸反应在以下情况下持续存在：（1）在心包囊内注入利多卡因后；（2）双侧颈迷走神经切断术后，提示它们是由于刺激了具有交感传入神经的非心脏受体。结论是，右心房注射辣椒素引发的初始呼吸反应是由于迷走神经传入纤维刺激肺C纤维受体所致。
