Age-dependent vulnerability to carotid chemodenervation in
piglets.
C[circumflex]ot[acute]e, Aurore, Hernan Porras, and Brian Meehan.
Jeremy Rill Center and Division of Respiratory Medicine, Department
of Pediatrics, Montreal Children's Hospital
APStracts 2:0367A, 1995.
We sought to determine the age of greatest vulnerability in piglets to
loss of carotid chemoreceptor function. We studied four groups of
carotid-body-denervated (CBD) piglets, whose carotid bodies were
surgically removed at 4 to 5, 9 to 10, 12 to 15, and 21 to 22 days
and who are herein referred to, respectively, as groups CBD5, CBD10,
CBD15, and CBD20. Four INTACT groups, at corresponding ages,
underwent a sham surgical procedure. After a post-surgery recovery of
at least seven days, we studied all animals to detect the presence of
apnea and the consequences of it, if any. Two days prior to the
experiments, we had implanted in all animals a fiberoptic arterial
catheter for continuous monitoring of arterial O2 saturation (SaO2),
and EEG electrodes for the recording of sleep states. During quiet
sleep, in the CBD15 group, we found numerous prolonged central apneic
events, accompanied by a profound desaturation, tachycardia, a rise
in blood pressure, and, eventually, a flattening of the EEG. No
prolonged apneic events occurred, however, in the other CBD groups,
nor in the INTACT animals. During active sleep, no prolonged apneic
events occurred at all. We thus conclude that, in piglets, the
absence of normally functioning carotid chemoreceptors at
approximately two weeks of age can lead to life-threatening apneic
events with severe hypoxemia, events that are state-specific.
Received 20 March 1995; accepted in final form 9 August 1995.
APS Manuscript Number A297-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.