| Objective: As a kind of stable and effective method of blood vessel restruction, coronary artery bypass graft(CABG) has been used widely in curing conary heart disease, but its long-term effect is not ideal. Many studies confirmed that after vascular remodeling surgery, constriction and clog of autologous venous graft is mainly caused by hyperplasia of endangium. Restenosis of venous graft results from damage of inner membrance of blood vessel, which is caused by vascular smooth muscle proliferate excessively and a large number of extracellular matrix secrete. It means that restenosis is a sort of physical injury after surgery that result in prothetic reaction of partial blood vessel after ischemia reperfusion injury, which is a prosses of vascular remodeling. Therefore, it is an effective measure that proliferation of vascular smooth muscles are obstructed to prevent venous graft from restenosis after CABG surgery.A mass of studies confirmed that atorvastatin can prevent vascular smooth muscle from proliferating, so that we reckon it is possible to block restenosis of venous graft after CABG surgery, but its mechanism fail to be certified. NF-κB is detected from the nucleus of B lymphocytes which is associated with the enhancer of immunoglobulin к light chain. In most cells, NF-κB is present as a latent, inactive, IκB-bound complex in the cytoplasm. When a cell receives any of a multitude of extracellular signals, NF-κB rapidly enters the nucleus and activates gene expression, and it participate in physiopathologic processes such as immunoregulation,inflammatory reaction, free radical injury and apoptosis. In addition, some studies have found that when endangium is damaged, various inflammatory mediator and cytokines are released and NF-κB is actived which make vascular smooth muscle cells and endotheliocyte up-regulation. Consequently, it make endangium proliferate that result in stenosis of vascular lumen. However, it is necessary to elucidated that whether restenosis of venous graft is caused by proliferation of vascular endotheliocyte via NF-κB pathway. Therefore, the study is aimed to observe whether restenosis of venous graft is caused by proliferation of vascular endotheliocyte via it and the role of atorvastatin in venous graft.Method: Fourty adult male New Zealand rabbit(2.5-3.5 kg) were used, and then animal model of autologous venous grafting were built.1 Atorvastatin has an inflenced on thickness, cells and ultrastructure of vascular intima of venous graft.The details are as follows: ①sham group(n=10): only vena jugularis externa was seprated, and then the rabbits were poured into normal saline through stomch tube ond day after sham operation; the rabbits were poured ②into normal saline through stomch tube ond day after venous graft surgery; ③atorvastatin 5 mg group(n=10): the rabbits were poured into atorvastatin 5 mg/kg.d through stomch tube ond day after venous graft surgery; ④ atorvastatin 10 mg group(n=10): the rabbits were poured into atorvastatin 10 mg/kg.d through stomch tube ond day after venous graft surgery.Each group was dealed with four weeks, after that HE stain, immunohistochemical and electron microscope were applied for observing atorvastatin how to affect thickness, cells and ultrastructure of vascular intima of venous graft.2 Atorvastatin has an influence on the expression of NF-κB p50 protein, NF-κB p50/p65 dimeric complexsThe groups were as follows: ①sham group(n=10): only vena jugularis externa was seprated, and then the rabbits were poured into normal saline through stomch tube ond day after sham operation; the rabbits were poured ②into normal saline through stomch tube ond day after venous graft surgery; ③atorvastatin 5 mg group(n=10): the rabbits were poured into atorvastatin 5 mg/kg.d through stomch tube ond day after venous graft surgery; ④atorvastatin 10 mg group(n=10): the rabbits were poured into atorvastatin 10 mg/kg.d through stomch tube ond day after venous graft surgery.Each group was dealed with four weeks, after that western blot and Co-immunoprecipitation(COIP) were applied for observing atorvastatin how to affect the expression of NF-κB p50 protein, and NF-κB p50/p65 dimeric complexs.Results:1 Atorvastatin has an inflenced on thickness of vascular intima of venous graft.Under light microscope, thickness of vascular intima of venous graft was observed by HE stain after surgery.Comprared with sham group(Fig.1), vascular wall of venous graft in control goup(Fig.2), atoravastatin 5mg group(Fig.3) and atoravastatin 10 mg group(Fig.4) all incrassate in different exent(P<0.05). Comprared with sham group(Fig.1), vascular wall of venous graft in control goup(Fig.2) obviously incrassate(P<0.01). There was no significant difference between atoravastatin 5mg group and control group(P> 0.05). However, vasscular wall of venous graft was smooth in atoravastatin 10 mg group(P <0.05).2 Atorvastatin has an inflenced on cells of vascular intima of venous graft.Under light microscope, cells of vascular intima of venous graft was observed by immunohistochemical after surgery.Comprared with sham group(Fig.5), the vascular wall and the smooth muscle cells of venous graft in control goup(Fig.6), atoravastatin 5mg group(Fig.7) and atoravastatin 10 mg group(Fig.8) all profliferated in different exent(P<0.05). The dyed sepia cells in atoravastatin 5mg group were a little less than that in control group(P> 0.05) and the cells in atoravastatin 10 mg group were much less than that in control group(P <0.05).3 Atorvastatin has an inflenced on ultrastructure of vascular intima of venous graft.Under electron microscope, ultrastructure of vascular intima of venous graft was observed after surgery.Compared with control group(Fig.9), vascular intima of venous graft incrassated a certain extent in atoravastatin 5mg group, but no significant difference was observed(P>0.05). However, it was continuous and smooth in atoravastatin 5mg group, with less arganelle(P <0.01).4 Atorvastatin has an inflenced on the expression of NF-κB p50 proteinThe expression of NF-κB p50 protein has been detected by western blot method after venous grafting surgery.A certain amount of NF-κB p50(Fig.12)protein was observed at all groups. Compared with the sham group, the expression of the protein was all up-regulated in other groups(P<0.05). At the same time, compared with the control group, the expression of the protein was down-regulated in atoravastatin 5 mg group, but there was no significant difference between the two group(P>0.05). The expression in atoravastatin 10 mg group was still higher than that of in sham group.(P<0.05).Above results showed that, atoravastatin could significantly down- regulate the expression of NF-κB p50 protein.5 Atorvastatin has an inflenced on the expression of NF-κB p50/p65 dimerThe expression of NF-κB p50/p65 dimer has been detected by Co-immunoprecipitation(COIP) method after venous grafting surgery.The expression of NF-κB p50/p65 dimer was observed in each group(Fig.12), and the dimmer expressed the most in control group of all the groups. Compared with sham group, the expression of NF-κB p50/p65 dimer significantly up-regulated in control group(P<0.01). Despite a descent was observed, the expression of NF-κB p50/p65 dimer in atoravastatin 5 mg group was still higher than that of in sham group(P<0.05). And, there was a significant difference on the expression of the dimmer between control group and atoravastatin 10 mg group(P<0.01).Above results showed that, atoravastatin could significantly down- regulate the expression of NF-κB p50/p65 dimer.Summary:1 NF-κB was significantly activeted, which up-regulating the expression of NF-κB p50 protein, appeared forming active dimers, nuclear translocation from cytoplasm after venous grafting surgery.2 Dealed With 10 mg atoravastatin, the expression of both NF-κB p50 protein and NF-κB p50/p65 dimers are down-regulated.Conclusion: Restenosis of venous graft is caused by proliferation of vascular endotheliocyte via NF-κB pathway after venous grafting surgery. And atorvastatin plays a role in protecting venous graft via the pathway. |
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