Effects of inspired gas on sleep-related apnea in the rat.
Christon, James, David W. Carley, Daniel Monti, and Miodrag
Radulovacki.
Departments of Medicine and Pharmacology, University of Illinois at
Chicago
APStracts 3:0068A, 1996.
Central apneas have been reported to occur in the rat during all
stages of sleep. Two types of apnea have been described: spontaneous
and post-sigh, which are immediately preceded by an augmented breath.
We studied the effect of inspired gas on the number and type of
apneas in nine adult male Sprague-Dawley rats which were surgically
prepared with cortical electroencephalogram (EEG) and nuchal
electromyogram (EMG) electrodes. In addition to EEG and EMG, we
recorded respiration by the barometric method using a single chamber
plethysmograph. Each rat was recorded from 10:00 until 16:00 on 4
separate days using different inspired gases: room air, 100% O2, 15%
O2 and 5% CO2. We found that the sleep-related apnea index was
significantly higher on 100% O2 as compared to room air (p <
.05) and were significantly lower on 15% O2 and 5% CO2 as compared to
room air (p < .05). Post- sigh apneas occurred more frequently
than spontaneous apneas (p < .0001). The coupling between sighs
and apneas was strengthened by hyperoxia and weakened by hypoxia and
hypercapnia (p < .05 for each). We conclude that stimulation of
chemoreceptors acts to oppose apnea in the rat.
Received 13 June 1995; accepted in final form 18 January 1996.
APS Manuscript Number A625-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96