Sleep-Wake State Organization in Infant Rats with Episodic Respiratory Disturbance Following Sinoaortic Denervation

Abstract

Summary: The role of arterial chemoreceptors in the maintenance of rhythmic respiration during sleep was investigated in 2-week.-old rats by microsurgical sectioning of carotid sinus and aortic depressor nerve fibers (SAD) and later recording of respiratory pattern by impedance pneumography and sleep-wake states by electrophysiological methods. Deafferentation produced high rates of an atypical respiratory pattern characterized by episodes during which the usual pattern was replaced by an arrhythmic series of low amplitude waveforms with frequent short pauses and occasional gasps. These episodes lasted a mean of 20 s, occurred 15.1 times/h and were virtually confined to the REM state. Apneas occurred in all stages of sleep and were not increased by SAD but were significantly associated with state changes only after denervation. Body movements were unchanged and sleep-wake state organization was only minimally affected by SAD. These results suggest that the REM state may constitute a vulnerable period for respiratory control in infancy during which afferent feedback from peripheral arterial chemoreceptors may ordinarily playa stabilizing role.

Contribution of baroreceptors and chemoreceptors to ventricular hypertrophy produced by sino‐aortic denervation in rats

“…structural) pulmonary hypertension in SAD rats, but does not rule out the possibility that transient pulmonary hypertension may occur in association with the most severe periods of hypoventilation over the course of a day. This possibility is supported by reports that intermittent alveolar hypoxia is sufficient to produce right ventricular hypertrophy in rats (Ostadal et al 1981) and that, in addition to the chronic hypoventilation that occurs in the waking state, more profound ventilatory disturbances (ventilatory arrhythmias, end expiratory pauses, apnoeas) occur during rapid eye movement sleep in SAD and CD rats (Hofer, 1985). However, it remains unclear why the CD and SAD groups should differ in these regards, since the SAD procedure should produce the same degree of chemoreceptor denervation as the CD procedure, if not greater.…”

“…This is surprising considering the negligible mortality following AD and the apparent absence of chemoreceptors in the aortic nerve of the rat (Sapru & Krieger, 1977;Martin-Body et al 1986;Franchini & Krieger, 1992. However, a similar interaction between AD and CD to increase mortality has been reported in neonatal rats (Hofer, 1985). The literature suggests that the occurrence of CD-and SADinduced mortality is variable from study to study.…”

Attenuation of the hypoxic ventilatory response in adult rats following one month of perinatal hyperoxia.

“…Sino-aortic denervation causes profound disruption of ventilatory pattern and a high incidence of mortality in neonatal sheep (Bureau, Lamarche, Foulon & Dalle, 1985), rats (Hofer, 1984(Hofer, , 1985(Hofer, , 1986 and piglets (Donnelly & Haddad, 1990), suggesting that carotid body chemoreceptors or carotid sinus baroreceptors play a necessary role in the postnatal maturation of eupnoeic breathing. However, chemoreceptorversus baroreceptor-mediated effects cannot be differentiated using this experimental approach.…”