Arousal response to hypoxia in newborn mice

We examined the arousal response to 5% O-2 in newborn mice at several ages before and after peripheral chemoreceptor resetting namely, at 3, 12, and 4 8 h (n = 22 in each group). Breathing was measured by whole-body flow barom etric plethysmography. Sleep and arousal were determined behaviourally. We found that: (1) the arousal response was present in all age groups: (2) the arousal response occurred during the hypoxic ventilatory decline in all ag e groups, showing that mechanoreceptor input was not sufficient to trigger arousal: and (3) arousal latency was shorter after than before chemorecepto r resetting, suggesting a contribution of chemoreceptors to arousal. We con clude that arousal may contribute to the hypoxic ventilatory response in th e early postnatal period in mice and that it should be taken into considera tion in studies of ventilatory control maturation in newborns. (C) 2001 Els evier Science B.V. All rights reserved.