Respiratory motor responses to cranial nerve afferent stimulation in rats

Am J Physiol. 1996 Oct;271(4 Pt 2):R1054-62. doi: 10.1152/ajpregu.1996.271.4.R1054.


It was hypothesized that, because rats appear to lack a prominent disynaptic projection from the dorsal respiratory group to phrenic motoneurons (Phr), they would lack the short-latency excitation of Phr output seen in cats in response to stimulation of some cranial nerve afferents. Single-pulse superior laryngeal nerve (SLN) stimulation elicited a short-latency bilateral excitation of glossopharyngeal (IX) and hypoglossal (XII) nerves and an ipsilateral excitation of pharyngeal branch of vagus (PhX) in 67% of rats, but no excitation of Phr. Vagus (X) stimulation elicited a bilateral excitation of Phr and a predominantly ipsilateral excitation of IX and PhX. Single-pulse stimulation of SLN or X also elicited longer-latency, bilateral decreases in activity of all recorded nerves. Repetitive stimulation (50 Hz) of SLN or X suppressed inspiratory activity and prolonged expiration. Lung inflation (7.5 cmH2O) inhibited Phr and PhX activity; X stimulation inhibited Phr but prolonged PhX activity. In conclusion, rats predictably lack the SLN-induced short latency Phr excitation but exhibit other short latency reflexes for which the underlying circuitry is not clear.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Afferent Pathways / physiology
  • Animals
  • Deglutition / physiology
  • Electric Stimulation / methods
  • Glossopharyngeal Nerve / physiology*
  • Hypoglossal Nerve / physiology*
  • Laryngeal Nerves / physiology
  • Lung / physiology
  • Male
  • Motor Neurons / physiology
  • Phrenic Nerve / cytology
  • Phrenic Nerve / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Respiration
  • Respiratory Muscles / physiology*
  • Vagus Nerve / physiology