Laryngeal Chemoreflex: Anatomic and Physiologic Study by use of the Superior Laryngeal Nerve in the Piglet

Abstract

The laryngeal chemoreflex (LCR) was investigated in 21 piglets (ages 6 to 80 days old) with the use of physiologic and histologic techniques. The central projection of the superior laryngeal nerve (SLN) was determined in 14 animals by use of horseradish peroxidase-wheat germ agglutinin. Ipsilateral labeling of the solitary tract nucleus was seen. The caudal extent of the labeling varied with age. Sensory labeling of the nucleus ambiguus was present bilaterally in three younger animals and unilaterally in older piglets. Bilateral labeling of the nucleus dorsomedialis was seen in all ages. Apneic and cardiovascular response to water stimulation of laryngeal mucosa and the laryngeal adductor reflex (LAR) were examined in 16 piglets. Blunting of the apneic and cardiovascular response was seen after sacrifice of a single SLN. Hypoxia did not significantly affect the LAR or apnea duration in animals with only one intact SLN. A contralateral LAR was found in younger animals. Relevance to the LCR is also discussed.

Synaptic events in ventral respiratory neurones during apnoea induced by laryngeal nerve stimulation in neonatal pig.

“…However, the actual identity of the neurones relaying early postsynaptic potentials to the respiratory neurones in the nucleus ambiguus remains to be determined. In the neonatal piglet afferent fibres from the SLN have been reported to end also in the proximity of the nucleus ambiguus (Goding, Richardson & Trachy, 1987) and therefore a shorter pathway from SLN afferents to neurones of the VRG may exist in neonates.…”

Protective Glottic Closure: Biomechanical Effects of Selective Laryngeal Denervation

“…A pig larynx model was selected because of its anatomic and physiologic similarities to that of humans. 7,8 Intraperitoneal pentobarbital sodium (20 to 30 mg/ kg body weight) was used for induction of anesthesia. To maintain anesthesia, we administered inhalational isoflurane via a nose cone and equilibrated it at 0.5 minimal alveolar concentration while each subject maintained spontaneous respiration.…”

“…Supported in part by the Charles W. Ohse Endowment. This study was performed in accordance with the PHS Policy on Humane Care and Use ofLaboratory Animals, the NIH Guide for the Care and Use of Laboratory Animals, and the Animal Welfare Act (7 through an anterior pharyngotomy and held its pressure-sensitive tip at the midportion of the membranous vocal cords. The tip of the transducer was secured to the thyroid ala with 3-0 Dexon suture to avoid any displacement with movements of the vocal cords (Fig 1).…”

The Pharyngeal Plexus–Mediated Glottic Closure Response and Associated Neural Connections of the Plexus

“…The porcine model was selected because of its anatomic and neurophysiologic resemblance to the human. 8,9 Ketamine hydrochloride (30 mg/kg), xylazine hydrochloride (2.2 mg/kg), and telazol (4.4 mg/kg) were injected intramuscularly as induction agents. General anesthesia was then provided with isoflurane inhalation via a nose cone.…”