Reflex effects of isocapnic changes in ventilation on tracheal tone in awake dogs.
We studied the effects of passive, isocapnic changes in ventilation on tracheal smooth muscle tone in 3 awake and 6 anesthetized dogs. Ventilation was altered using mechanical ventilation under hyperoxic conditions, and tracheal tone was measured using the pressure within a water-filled balloon in an isolated segment of trachea. Hypocapnia was prevented at increased VA by increasing FICO2. When f and VT were changed reciprocally, keeping VA constant, tracheal tone did not change. However, when either for VT was changed independently, tracheal tone decreased with an increase in VA. This effect was abolished following thoracic vagotomy. We conclude that tracheal tone is reflexly decreased during an increase in VA.
D000818:Animals; D002245:Carbon Dioxide; D004285:Dogs; D005260:Female; D008297:Male; D009126:Muscle Relaxation; D009130:Muscle, Smooth / Q000502:physiology*; D011312:Pressure; D012018:Reflex; D012044:Regression Analysis; D012119:Respiration; D012121:Respiration, Artificial; D013990:Tidal Volume; D014132:Trachea / Q000502:physiology*; D014628:Vagotomy
D002245:Carbon Dioxide