Ravi K
Department of Physiology and Centre for Visceral Mechanisms, Vallabbhai Patel Chest Institute, University of Delhi, Delhi, India.
Can J Physiol Pharmacol. 1988 Jul;66(7):946-50. doi: 10.1139/y88-154.
The respiratory responses following stimulation of type J (pulmonary C fiber) receptors by right atrial injections of capsaicin were assessed in spontaneously breathing anesthetized dogs. At the reflexly effective threshold dose, the primary respiratory response elicited was tachypnoea. With higher doses of capsaicin, the tachypnoea was replaced by apnoea. Left atrial injections of capsaicin also resulted in apnoea, which was abolished or reduced by injecting Xylocaine into the pericardial sac, and after vagotomy, apnoea was replaced by tachypnoea. The latter findings suggested that the apnoea produced by left atrial injection of capsaicin might be due to stimulation of receptors with vagal afferents coursing through the pericardium. In vagotomized dogs, administration of capsaicin into the abdominal aorta above the origin of the iliac arteries (the iliac arteries were kept occluded) resulted in a hyperpnoeic response. Following the transection of the spinal cord between L4 and L5, capsaicin injection into the abdominal aorta caused apnoea instead of hyperpnoea. The apnoeic response elicited was abolished by transecting the spinal cord between L1 and L2. It is suggested that the respiratory responses observed were due to stimulation of receptors in the splanchnic bed connected to sympathetic afferents.
在自主呼吸的麻醉犬中，评估了通过右心房注射辣椒素刺激J型（肺C纤维）受体后的呼吸反应。在反射有效阈值剂量下，引发的主要呼吸反应是呼吸急促。使用更高剂量的辣椒素时，呼吸急促被呼吸暂停所取代。左心房注射辣椒素也会导致呼吸暂停，通过在心包囊内注射利多卡因可消除或减轻这种呼吸暂停，并且在迷走神经切断后，呼吸暂停被呼吸急促所取代。后一发现表明，左心房注射辣椒素产生的呼吸暂停可能是由于刺激了通过心包走行的迷走传入神经的受体。在迷走神经切断的犬中，在髂动脉起始部上方（髂动脉保持闭塞）将辣椒素注入腹主动脉会导致呼吸增强反应。在L4和L5之间横断脊髓后，向腹主动脉注射辣椒素会导致呼吸暂停而非呼吸增强。切断L1和L2之间的脊髓可消除引发的呼吸暂停反应。提示观察到的呼吸反应是由于刺激了与交感传入神经相连的内脏床中的受体。
