Cardiovascular and respiratory changes during slow-wave sleep in rats are associated with electrocorticogram...

In awake rats a single recurrent larger tidal volume (deep breaths) occurs at regular intervals, followed by oscillations in arterial pressure and heart rate. In the present study we recorded the changes in blood pressure, heart rate and ventilation during the wakefulness-sleep cycle identified by electrocorticographic records in order to determine whether the deep breaths and cardiovascular oscillations were associated 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 desynchronization. The interval between deep breaths during SWS was 71 +/- 4 s, the period between initial desynchronization and the generation of deep breaths 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 indicate that the oscillations in arterial pressure and heart rate during SWS are associated with deep breaths, which in turn are preceded by desynchronization of the electrocorticogram in this state of sleep.