Abstract: Objective To establish the rat overlap syndrome (OS) model of intermittent hypoxia (IH) and emphysema, explore systematic and endothelial inflammation status, and observe the change of endothelial progenitor cell (EPC) level. Methods Overlap exposure was IH exposure on the base of pre-existing emphysema which was caused by 16 weeks of smoke exposure. 60 male Wistar rats were randomly divided to four groups with 15 per group according to the exposure conditions as follows: normal oxygen control group (A); IH group (B); emphysema group (C); OS group (D). After exposure, ELISA method was used to detect values of tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6 in plasma and in the endothelium of right common carotid artery. Real-time-PCR assay was used to analyze RhoA mRNA level in the endothelium of right common carotid artery. Flow cytometry was used to detect EPC level. We also obtained tissue of right carotid artery for counting the percentage of intima-media thickness (IMT) in the all wall (C-IMT%). Results D group had highest values of TNF-α, IL-6, RhoA mRNA and C-IMT% among all groups. The quantity of EPC were highest in D group among all groups (all P < 0.05). Conclusion OS rats had more serious vascular endothelial injury than emphysema or IH rats. Meanwhile, the repair capacity of EPC for endothelium was the worst, which increase the risk of cardiovascular diseases.

Key words: intermittent hypoxia, emphysema, endothelial progenitor cell, TNF-α, IL-6, RhoA, intima-media thickness