Postnatal maturation of the peripheral chemoreceptor ventilatory
response to o2 and co2 in newborn lambs.
Canet, Emmanuel, Irenej Kianicka, and Jean-Paul Praud.
From the Pulmonary Research Unit, Department of Pediatrics and
Physiology, Faculty of Medicine, University of Sherbrooke, SHERBROOKE
(Quebec), Canada J1H 5N4
APStracts 3:0077A, 1996.
Although studies on lambs have shown that carotid body sensitivity to
O2 is reset postnatally, it is still unknown whether O2 and CO2
peripheral chemoreflexes undergo parallel postnatal maturation. The
present study was designed to analyze maturation of O2 and CO2
peripheral chemoreflexes in ten lambs at <24 hours of age and at
12 days. We measured the ventilatory (VE) response to 3 tidal breaths
of pure N2 or 13% CO2 in air. Overall, the N2 peripheral chemoreflex
increased significantly with maturation [VE/EtO2 (ml/min/kg/torr) =
2.94 +/- 0.91 at <24 hours vs 5.13 +/- 0.59 at 12 days,
p<0.05], while the CO2 peripheral chemoreflex did not change
(VE/EtCO2 = 7.04 +/- 0.98 at <24 hours vs 7.75 +/- 1.07 at 12
days, ns). We conclude that the CO2 peripheral chemoreflex does not
change in awake lambs within the time frame studied, in contrast to a
marked postnatal maturation of the O2 peripheral chemoreflex. The
different time-courses of O2 and CO2 peripheral chemoreflex
maturation support the concept that carotid body sensitivities to O2
and CO2 do not depend on the same basic mechanisms.
Received 24 July 1995; accepted in final form 4 January 1996.
APS Manuscript Number A807-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96