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  • Title: Attenuation of hypoxic ventilation by hyperbaric O2: effects of pressure and exposure time.
    Author: Liberzon I, Arieli R, Kerem D.
    Journal: J Appl Physiol (1985); 1989 Feb; 66(2):851-6. PubMed ID: 2708214.
    Abstract:
    Hyperoxia affects O2 chemoreception in the highly perfused carotid bodies and causes a reduction of the ventilatory hypoxic drive (HD) as was shown for anesthetized cats and awake rats. We looked for a quantitative description of such an effect on HD as a function of both O2 pressure and exposure duration. Ventilation of rats was measured using the barometric method before and after hyperbaric O2 (HBO) exposure, at either air, 80% O2, or 4% O2. We used three exposure durations: 180, 550 and 900 min. The O2 pressure ranged between 1.2 and 3.0 ATA. At each time duration we used four to five groups of rats at a range of O2 pressures that yielded the full scale of effect on HD but avoided obvious lasting difficulties in breathing. HBO caused a reduction of breathing frequency and elevation of tidal volume in both air and 80% O2 but almost no change in minute ventilation. Hypoxic minute ventilation (4% O2) decreased after HBO, mainly through reduced frequency. HD was described by a power function of O2 pressure for each HBO duration. HD did not decline below 20% of the full control response. Ventilatory HD diminution is pictured as a function of both O2 pressure and HBO duration. The dependency of HD on exposure time and on pressure is similar to other known toxic effects of HBO.
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