Effect of prior o2 breathing on ventilatory response to sustained
isocapnic hypoxia in adult humans.
Honda, Y., H. Tani, A. Masuda, T. Kobayashi, T. Nishino, H. Kimura, S.
Masuyama, and T. Kuriyama.
Department of Physiology, Department of Anesthesiology and
Department of Chest Medicine, School of Medicine, Chiba, University,
Chiba, 260 Japan and Chiba College of Allied, Sciences, Chiba, 260
Japan
APStracts 3:0267A, 1996.
Sixteen healthy volunteers first breathed either 100% O2 or room air
for ten min in random order, and then their ventilatory response to
sustained normocapnic hypoxia (Spo2 80%) was studied for 20 min. In
addition, to detect agents possibly responsible for the respiratory
changes, 10 of the 16 subjects also underwent chemical analysis of
blood plasma. 1) Preliminary O2 breathing uniformly and substantially
augmented hypoxic ventilatory responses. 2) However, the profile of
ventilatory response in terms of relative magnitude, i.e., biphasic
hypoxic ventilatory depression, remained nearly unchanged. 3)
Augmented ventilatory increment by prior O2 breathing was
significantly correlated with increment in the plasma glutamine
level. We conclude that preliminary O2 administration enhances
hypoxic ventilatory response without affecting the biphasic response
pattern, and speculate that excitatory amino acid neurotransmitter
glutamate possibly derived from augmented glutamine may, at least in
part, play a role in this ventilatory enhancement.
Received 5 December 1995; accepted in final form 13 May 1996.
APS Manuscript Number A1261-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 17 June 96