Laryngeal-receptor responses to phasic CO2 in anesthetized cats.
We compared the effects of CO2 applied continuously and during expiration on laryngeal-receptor activity in paralyzed, artificially ventilated and nonparalyzed, spontaneously breathing cats by using an isolated larynx, artificially ventilated to approximate a normal respiratory cycle. The majority of quiescent negative-pressure and all cold receptors were excited by 5 and 9% CO2 applied both continuously and during expiration. In general, quiescent positive-pressure, tonic negative-pressure, and tonic positive-pressure receptors were inhibited by 5 and 9% CO2 applied continuously and during expiration. There were no significant differences between responses to 5 and 9% CO2 or to continuous and expired CO2 or between paralyzed and nonparalyzed preparations. In conclusion, laryngeal receptors respond to changes in CO2 concentration occurring during a normal respiratory cycle. Because laryngeal-receptor stimulation exerts reflex effects on ventilation and upper airway muscle activity, these results suggest that airway CO2 plays a role in reflex regulation of breathing and upper airway patency.
Bradford
A
A
Department of Physiology, Royal College of Surgeons in Ireland. abradfor@rcsi.ie
McKeogh
D
D
O'Regan
R G
RG
D000758:Anesthesia; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism*; D002415:Cats; D003080:Cold Temperature; D005260:Female; D007823:Laryngeal Nerves / Q000502:physiology; D007830:Larynx / Q000502:physiology*; D008297:Male; D009412:Nerve Fibers / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology; D014132:Trachea / Q000502:physiology
D002245:Carbon Dioxide