CARDIOVASCULAR AND RESPIRATORY CHANGES DURING SLOW-WAVE SLEEP IN RATSARE ASSOCIATED WITH ELECTROCORTICOGRAM DESYNCHRONIZATION

In awake rats a single recurrent larger tidal volume (deep breaths) oc curs at regular intervals, followed by oscillations in arterial pressu re and heart rate. In the present study we recorded the changes in blo od pressure, heart rate and ventilation during the wakefulness-sleep c ycle identified by electrocorticographic records in order to determine whether the deep breaths and cardiovascular oscillations were associa ted with changes in the electrocorticogram. During several episodes of slow-wave sleep (SWS) in 7 rats the deep breaths and oscillations in arterial pressure and heart rate were preceded by SWS desynchronizatio n. The interval between deep breaths during SWS was 71 +/- 4 s, the pe riod between initial desynchronization and the generation of deep brea ths was 3.98 +/- 0.45 s and the duration of SWS desynchronization was 11 +/- 0.65 s. Hypotension (-16 +/- 1 mmHg) and tachycardia (+15 +/- 5 bpm) were observed during deep breaths in the SWS state. These data i ndicate that the oscillations in arterial pressure and heart rate duri ng SWS are associated with deep breaths, which in turn are preceded by desynchronization of the electrocorticogram in this state of sleep.