Long-term variations of arterial blood pressure during sleep in freely moving cats

Using a new telemetric system for arterial blood pressure recordings, we have investigated long-term postoperative changes in blood pressure during sleep in freely moving cats. Particular attention was paid to the transitional periods at the beginning and end of paradoxical sleep (PS), as well as to the relationship between the blood pressure and ponto-geniculo-occipital (PGO) waves. In the initial postoperative stage lasting 2 to 5 days, the blood pressure decreased during the transition from slow wave sleep (SWS) to PS and maintained its lower level until the end of PS. In contrast, in the later chronic stage, the blood pressure increased tonically during the transition from SWS to PS and maintained its higher level throughout PS on which several phasic rises in blood pressure were superimposed. A significant increase in arterial pressure during the transitional period began shortly after the first appearance of PGO waves. On the other hand, significant phasic rises in arterial pressure during PS shortly preceded the onset of PGO wave bursts.