Abstract: AIM: To investigate the effect of angiotensin-(1-7) on intimal hyperplasia and blood flow in carotidartery after adventitia removal in SHR.METHODS: Twenty-four spontaneously hypertensive rats(SHR) with right carotid artery adventitia removed were randomly divided into 3 groups (n =8, each):Ang-(1-7), Ang779 and SHR control group.Eight Wistar-Kyoto rats were selected as normal control grouP(WKY group).Adventitia in right carotid artery was removed by mechanical and chemical means.Adventitia in left carotid artery was sham-operated. Ang-(1-7) in saline (25μg·kg^-1·h^-1) was infused intravenously for 14 days.The systolic blood pressure (SBP) was taken.The velocity of carotid artery was detected by electromagnetic rheometer.Plasma and carotid artery angiotensin II (Ang Ⅱ)levels were measured by radioimmunoassay.The intimal hyperplasia was measured by computed video processing.The expression of local angiotensin II type 1 receptor(AT1R) protein in both arteries was determined by immunohistochemistry method.The apoptosis of vascular tissue cell in carotid artery was evaluated by terminal deoxynucleotidyl transferase-mediated DutPnick-end labeling(TUNEL) assay and measured by image analyse system.RESULTS: SBPin Ang-(1-7) grouPwas significantly lower than that in Ang779 and SHR grouP(all P<0.01).Compared with Ang779 and SHR group, the carotid blood flow in no adventitia removal in Ang-(1-7)grouPwas increased significantly (P<0.01).Compared with no adventitia removal, the intimal hyperplasia in adventitia removal was exacerbated significantly (P<0.05), and it was markedly inhibited in Ang-(1-7)grouP(P<0.01).Carotid artery Ang Ⅱlevel in adventitia removal was significantly higher than that in no adventitia removal (P<0.01).Ang-(1-7) had no significantly effect on plasma and local Ang Ⅱlevels (P>0.05).The expression of AT1R protein in adventitia removal was significantly higher than that in no adventitia removal in SHR and Ang779 group.Compared with Ang779 and SHR group, the expression of AT1R protein in Ang-(1-7) grouPwas down-regulated significantly (all P<0.01).Compared with Ang779 and SHR group, apoptotic index in adventitia removal and no adventitia removal in Ang-(1-7) grouPwas increased significantly (all P<0.01).CONCLUSION: Ang-(1-7) can significantly improve intimal hyperplasia and increase blood flow in carotid artery with adventitia removal in SHR, which may be related to the down-regulation of local AT1 R protein.

Key words: angiotensin-(1-7), rats, carotid artery, adventitia, angiotensin II type 1 receptor, apoptosis