Impact of cervical spinal contusion on the upper airway resistance in the rat

Abstract

Bronchopulmonary C‐fiber induced pulmonary chemoreflex is a critical component of the respiratory defense reflex and characterized by cessation of inspiratory airflow (i.e., apnea) and increase of upper airway resistance (i.e., laryngeal closure). Our previous reports demonstrated that apneic response was attenuated following cervical spinal cord injury; however, it remained unclear whether the upper airway response of pulmonary chemoreflex was also influenced by spinal injury. Accordingly, the present study was designed to investigate the response of laryngeal function to bronchopulmonary C‐fiber activation following unilateral high‐cervical spinal cord contusion in rats. Adult Sprague–Dawley male rats were received laminectomy or unilateral contusion at C2 spinal cord using the MASCIS Impactor (height: 6.25 mm). The respiratory airflow and subglottal pressure in response to intra‐jugular capsaicin (1.5 μg/kg)‐induced pulmonary chemoreflex were measured under spontaneously breathing condition at 3 days, 2 weeks or 6 weeks following spinal surgery. The result demonstrated that high cervical contusion caused a long‐term reduction in the tidal volume without alteration of laryngeal resistance at three time points after injury. However, capsaicin‐induced increase of subglottal pressure was substantially attenuated in contused animals at 3 days post‐injury, and partially recovered at 2 and 6 weeks post‐injury. These results suggested that cervical spinal cord injury not only influence the breathing pattern but also impact the upper airway function. The attenuated laryngeal closure response may unfavorably reduce the ability to prevent inhaling irritants and cause the pulmonary pathological condition following cervical spinal cord injury.Support or Funding InformationMOST 105‐2628‐B‐110‐002‐MY3This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.