Interaction of chemical and state effects on ventilation during
sleep onset.
Dunai, Judith, Mal Wilkinson, and John Trinder.
Dept. of Psychology, School of Behavioural Science, University of
Melbourne, Melbourne, Australia, Centre for Early Human Development,
Monash University Medical Centre, Clayton, Australia
APStracts 3:0376A, 1996.
Ventilation varies as a function of state, being higher during
wakefulness (as indicated by alpha EEG activity) than during sleep
(theta activity). A recent experiment observed a progressive increase
in the magnitude of these state related fluctuations in ventilation
over the sleep onset period (28). The aim of the present experiment
was to test the hypothesis that this effect resulted from chemical
(feedback related) amplification of state effects on ventilation. A
hyperoxic condition was used to eliminate peripheral chemoreceptor
activity. It was hypothesised that hyperoxia would reduce the
amplification of changes in ventilation associated with EEG state
transitions. Ventilation was measured over the sleep onset period
under both hyperoxic and normoxic conditions in ten, young, healthy
male subjects. Sleep onsets were divided into three phases. Phase 1
corresponded to pre-sleep wakefulness, and phases 2 and 3 to early
and late sleep onset respectively. The magnitudes of state related
changes in ventilation during phases 2 and 3 and under hyperoxic and
normoxic conditions were compared using a phase by condition analysis
of variance. Results revealed a significant phase by condition
interaction, confirming that hyperoxia reduced the amplification of
state related changes in ventilation by selectively decreasing the
magnitude of phase 3 state changes in ventilation. However, some
degree of amplification was evident during hyperoxia, thus the
results demonstrated that peripheral chemoreceptor activity
contributed to the amplification of state related changes in
ventilation, but that additional factors may also be involved.
Received 12 July 1995; accepted in final form 10 April 1996.
APS Manuscript Number A755-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996