title: Analysis of respiratory patterns in the awake and in the halothane anaesthetised rat.
abstract: Respiratory patterns have been studied in awake and halothane anaesthetised rats. Tidal volume (VT) was shown to be age-sensitive over 44-200 days; failure to account for this gave the appearance of an increased ventilatory sensitivity to CO2 with age. Inspiration of CO2 (0-10.5%) produced linear responses of VT whereas frequency responses stabilised at 6% CO2. Initially expiratory duration (TE) decreased more than inspiratory duration (TI) and both decreased linearly relative to increased VT; above 6% CO2, increases in VT occurred with only minor changes in TI and TE. Halothane anaesthesia dominantly depressed the frequency response to CO2. We conclude that the rat shows a great influence of vagal control on breathing in the awake state and in halothane anaesthesia; that TE is controlled independently of TI; and that respiratory frequency is more rigorously controlled than VT.
mesh_terms: D000375:Aging; D000768:Anesthesia, General; D000818:Animals; D002245:Carbon Dioxide; D003243:Consciousness; D005260:Female; D006221:Halothane; D051381:Rats; D011919:Rats, Inbred Strains; D012119:Respiration; D013990:Tidal Volume; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D006221:Halothane