title: Respiratory interneurons in the C5 segment of the spinal cord of the cat.
abstract: Extracellular recordings were made in the C5 segment of the spinal cord of anaesthetised cats from 129 units which showed respiratory phased discharge. The majority of recordings (88%) were thought to arise from the somata of respiratory spinal interneurons. Inspiratory units and expiratory units comprised 42% and 52% of all recorded units. A small number of postinspiratory units were also found (n = 5). Most units did not respond to electrical stimulation of the ipsilateral superior laryngeal (SLN) and phrenic nerves (PN), but a few expiratory (n = 2) and postinspiratory units (n = 1) were excited by SLN stimulation, while 6 inspiratory units had their discharge suppressed by the same stimulus. PN stimulation evoked a long latency (2-7 ms) burst of firing in 2 inspiratory and 1 expiratory interneurons. It is concluded that these respiratory interneurons may provide a segmental input to phrenic motoneurons, in addition to synaptic drives mediated by bulbospinal pathways.
authors.affiliation: Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT.
authors.forename: M C
authors.initials: MC
authors.lastname: Bellingham
authors.forename: J
authors.initials: J
authors.lastname: Lipski
mesh_terms: D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D007395:Interneurons / Q000502:physiology*; D007823:Laryngeal Nerves / Q000502:physiology; D010791:Phrenic Nerve / Q000502:physiology; D012137:Respiratory System / Q000294:innervation*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*