EFFECTS OF HYPOXIA ON RESPIRATORY DEFENSE REFLEXES - EFFECTS OF 30 HOURS OXYGEN DEFICIENCY ON COUGH, THE EXPIRATION REFLEX AND SNEEZING IN AWAKE CATS

  • 1 January 1985
    • journal article
    • research article
    • Vol. 34  (1) , 41-48
Abstract
The expiration reflex (ER); tracheobronchial (TB) and laryngopharyngeal (LPh) cough; the respiratory rate (f), tidal volume (VT); the end tidal fractional CO2 concentration of (FETCO2); the pH; the blood gases and the heart rate were studied in 11 adult cats during 30 h: isobaric hypoxic hypoxia (FO2 = 0.11). During the 30 h, the cats developed hypocapnic hypoxemia, f remained unchanged and VT was markedly elevated. In the acute phase (15 min) of hypoxic hypoxia of the same intensity, changes in respiratory parameters were the same and the intensity of respiratory reflexes increased significantly (Tatar et al. 1984). During prolonged hypoxic hypoxia there were no significant changes in the intensity of the ER and of TB and LPh cough. Some adaptation of the central mechanisms regulating the defence reflexes of the airways may take place. An increase in the susceptibility of the cough center during constant conditions of the stimulation of cough receptors would not be biologically expedient. The different changes in the intensity of respiratory defence reflexes in the acute and the prolonged phase of hypoxic hypoxia with identical changes in respiratory parameters support are the existence of functional differences between the respiratory center and the cough center.