Influence of carotid-denervation on the arousal and cardiopulmonary responses to alveolar hypercapnia in lambs.
Experiments were done on five lambs to determine if carotid-denervation influences the arousal and cardiopulmonary responses to alveolar hypercapnia during sleep. Each lamb was anaesthetized and instrumented for recordings of electrocorticogram, electro-oculogram, nuchal and diaphragm electromyograms and measurements of systemic arterial blood pressure and arterial haemoglobin oxygen saturation. The carotid chemoreceptors and baroreceptors were denervated, a tracheostomy was done and a fenestrated tracheostomy tube placed in the trachea so that the inspired gas mixture could be changed quickly. No sooner than three days after surgery, measurements were made in quiet sleep and active sleep during control periods when the animal was breathing room air and during experimental periods of alveolar hypercapnia when the lamb was breathing 10% carbon dioxide in air. Alveolar hypercapnia was terminated during an experimental period by changing the gas mixture back to room air once the animal aroused from sleep. If an animal did not arouse within 2 min, the gas mixture was changed back to room air. Arousal occurred during only 6 of 12 epochs in quiet sleep and during only 2 of 10 epochs in active sleep. These data provide evidence that the carotid chemoreceptors and/or carotid baroreceptors play a major role in causing arousal from sleep during alveolar hypercapnia in lambs.
Fewell
J E
JE
Department of Obstetrics and Gynaecology, University of Calgary Health Sciences Centre, Alberta, Canada.
Kondo
C S
CS
Dascalu
V
V
Filyk
S C
SC
D000818:Animals; D001049:Apnea / Q000503:physiopathology; D001143:Arousal / Q000502:physiology*; D002344:Carotid Body / Q000502:physiology*; D002346:Carotid Sinus / Q000294:innervation*; D002628:Chemoreceptor Cells / Q000502:physiology; D003714:Denervation; D004195:Disease Models, Animal; D004594:Electrophysiology; D006321:Heart / Q000502:physiology; D006935:Hypercapnia / Q000503:physiopathology*; D011311:Pressoreceptors / Q000502:physiology; D012119:Respiration / Q000502:physiology; D012756:Sheep