title: Effects of hypoxia and hypercapnia on nonnutritive swallowing in newborn lambs.
abstract: The aim of the present study was to investigate the effect of hypercapnia and hypoxia on apnea and nonnutritive swallowing (NNS) frequency, as well as on the coordination between NNS and phases of the respiratory cycle in newborn lambs, while taking into account the potential effects of states of alertness. Six lambs were chronically instrumented for recording electroencephalogram, eye movements, diaphragm and thyroarytenoid muscle (a glottal adductor) activity, nasal airflow, and electrocardiogram. Polysomnographic recordings were performed in nonsedated lambs exposed to air (control), 10% O(2), and 5% CO(2) in a random order at 3, 4, and 5 days of age. Although hypercapnia decreased apnea frequency in wakefulness and active sleep (P = 0.002 vs. air and hypoxia), hypoxia had no significant effect on apnea. In addition, although hypercapnia increased NNS frequency during wakefulness and quiet sleep (P < 0.005 vs. air and hypoxia), hypoxia tended to decrease NNS frequency. Finally, only hypercapnia altered NNS-breathing coordination by increasing NNS at the transition from inspiration to expiration (ie-type NNS; P < 0.001 vs. air and hypoxia). In conclusion, whereas hypercapnia increases overall NNS frequency by specifically increasing ie-type NNS, hypoxia has the inverse tendency. Results were identical in all three states of alertness.
authors.affiliation: Department of Pediatrics and Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
authors.forename: Charles
authors.initials: C
authors.lastname: Duvareille
authors.forename: Mylène
authors.initials: M
authors.lastname: Lafrance
authors.forename: Nathalie
authors.initials: N
authors.lastname: Samson
authors.forename: Marie
authors.initials: M
authors.lastname: St-Hilaire
authors.forename: Patrick
authors.initials: P
authors.lastname: Pladys
authors.forename: Philippe
authors.initials: P
authors.lastname: Micheau
authors.forename: Véronique
authors.initials: V
authors.lastname: Bournival
authors.forename: Carole
authors.initials: C
authors.lastname: Langlois
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Praud
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001049:Apnea / Q000503:physiopathology; D003679:Deglutition / Q000502:physiology*; D003964:Diaphragm / Q000502:physiology; D004562:Electrocardiography; D004569:Electroencephalography; D005133:Eye Movements / Q000502:physiology; D006935:Hypercapnia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D012119:Respiration; D012756:Sheep / Q000502:physiology*; D012890:Sleep / Q000502:physiology; D013686:Telemetry / Q000379:methods; D014851:Wakefulness / Q000502:physiology