[Sleep-wake rhythm after extracorporeal circulation in 
New Zealand rabbits]

To evaluate the change of sleep-wake rhythm after extracorporeal circulation (ECC) in New Zealand rabbits, and to explore the role of clock genes in sleep-wake rhythm disorder by ECC.
 Methods: A total of 54 New Zealand rabbits were randomly divided into 3 groups: a normal group (Group N), a sham group (Group S) and a model group (Group ECC). Electrocorticogram (ECOG), electroophthalmogram (EOG) and electromyogram (EMG) were respectively recorded by multipurpose EEG recorder, and the sleep-wake rhythm was also recorded. The mRNA and protein expressions of period1 (Per1) and cryptochrome1 (Cry1) were detected by semi-quantitative reverse transcriptase PCR (RT-PCR) and Western blot in pineal gland of rabbits. The differences between the 3 groups were compared.
 Results: 1) Compared with the Group N and Group S at 24, 48 h respectively, the total amount of sleep (TAS), light time, slow wave sleep (SWS) in the Group ECC at 24, 48 h were significantly reduced (all P<0.05), and the proportion of light sleep increased (all P<0.05), the proportion of SWS decreased (all P<0.05); 2) Compared with the Group N and Group S, the expression of Per1 mRNA in the Group ECC at 24, 48 h and Cry1 mRNA at 24 h significantly increased (all P<0.05); 3) Compared with the Group N and Group S, the expression of Per1 protein in the Group ECC at 48 h and Cry1 protein at 24 h significantly increased (all P<0.05); 4) In the Group ECC, the sleep-wake rhythm disorder and clock genes expression were ameliorated at 72 h after surgery.
 Conclusion: ECC can cause sleep-wake rhythm disorder in New Zealand rabbits, which may be related to the abnormal expression of Per1 and Cry1, and their transcription proteins.