Journal of Applied Physiology, Vol 52, Issue 4 1030-1034, Copyright © 1982 by American Physiological Society
No effect of naloxone on hypoxia-induced ventilatory depression in adults
S. Kagawa, M. J. Stafford, T. B. Waggener and J. W. Severinghaus
The ventilatory response to acute isocapnic hypoxia is prompt but is not
maintained at its peak. Within 10 min, it begins to fall, and by 30 min has
reached an approximately steady level, usually still above control. We used
naloxone to test in four men the hypothesis that this fade is hypoxic
depression mediated by endogenous opioid peptides, e.g, endorphins. Breath
by breath minute ventilation was recorded during a hyperoxic control period
(FIO2 = 0.3) to establish control alveolar PCO2. After 15 min. of isocapnic
hypoxia (end-tidal PO2 = 45 Torr), naloxone injection (1.2 or 10 mg, iv)
failed to alter the slow decrement of ventilation. Hypoxic ventilatory
depression appears not to be mediated by endorphins in adults.
