Response of upper airway motor activities to negative airway pressure in the rat

• Main Author: 蔡欣曄
• Other Authors: 黃基礎
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/z83384

碩士 === 國立臺灣師範大學 === 生命科學研究所 === 96 === To study the effect of changes in airway pressure on upper airway motor nerve activities, adult rats of Wistar were used. The rat was anesthetized with urethane, paralyzed, and artificially ventilated. Catheterization was performed in the trachea, femoral artery and vein. The phrenic, recurrent laryngeal (RLN), and hypoglossal nerves, as well as the abducent (Abd) and adducent (Add) branches of the RLN were separated and their activities were recorded under normocapnia in hyperoxia. The outlet of the ventilator was placed under water surface with a deep of 3 cm such that a 3-cmH2O positive end-expired pressure (PEEP) was obtained to be used as the control. The airway pressure measured by the tracheal pressure (TP) was decreased to a level of continuous negative airway pressure (CNAP) and of negative end-expired pressure (NEEP) at -1 and -3 cmH2O with a water trap system, and then increased to PEEP at 6 cmH2O. The observed results showed that blood pressure and respiratory frequency were increased, and phrenic burst was not changed in immediate response to CNAP and PEEP, and that activity of the entire RLN was significantly increased during inspiratory and expiratory period. Data from the recording of the intralaryngeal branches showed that activity of the Add RLN was increased and also extended to the inspiratory duration such that it transformed into a tonic discharge pattern with CNAP and NEEP. Activity of the hypoglossal nerve was significantly and immediately decreased with CNAP and NEEP. Increase in PEEP at 6 cmH2O produced a decrease of blood pressure and respiratory frequency without conspicuous change in phrenic burst. Activity of the Add RLN and Abd RLN was decreased. There was no change in hypoglossal activity but displayed an advancement in onset. All these reflexive responses were totally abolished after bilateral vagotomy. These results showed that airway resistance may be increased due to the increase of activity of the Add RLN and the decrease of hypoglossal discharge and that this increase in airway resistance may benefit for the maintenance of lung volume.