Background : Transplant coronary artery disease remains a troublesome long term complication of heart transplantation .The character of GCAD is vascular narrowing resulting from intimal hyperplasia. The pathogenesis of intimal hyperplasia is thought to derive from an interation between immune and nonimmune factors ,leading to endothelial dysfunction and smooth muscle cells(SMCs) proliferation . Endothelin-1 (ET-1)is derived from vascular endothilium ,SMCs and macrophages .ET-1 has a wide range of biological and pathological functions . ET-1 stimulates constriction of SMCs and the proliferation of SMC . ET-1 induces the production of cytokines and growth factors such as endothelial growth factor,basic fibroblast growth factor and epiregulin .ET-1 also potentiates the effects of transforming growth factor-B and PDGF and interates with blood cells stimulating neutrophil adhesion and platelet agrregation .ET-1 ,predominantly via endothelin receptor A (ETA) ,promotes vasoconstriction ,cell growth ,cell adhesion and thrombosis ,thus ,ET-1 and ETA receptor is a pomising target for cardiovascular therapy . It has been demonstrated that ET-1 expression increased in the neointimal of coronary artery in allograft heart .However the role of ETA receptor in the pathogensis of GCAD is still unknown The study is to inverstigate changes of the expresssion of ETA in allograft carotid artery and blockade of ETA expression with antisense oligodeoxynuleutides of endothelin receptor A (AS-ETA- ODN) leading inhibition of intimal hyperplasia in the allograft carotid arteryPart I Transplant Artery Disease in An Rodent Model Objective: This study is to set up a arterial homeotransplant model . Method :Carotid artery of Wistar rat was transplanted into carotid artery of SD rat with microsurgical technique. After 1,2,3 4,and 6 weeks after transplantation ,the allograft artery was harvested and grafted artery pathologic histology was examinated .Result: After transplantation ,the animal survial rate was more 98%.The patency is 100% at time point of 2 weeks after transplantation . Pathologic histoloy showed that intimal hyperplasia could be seen in all allograft artery after 4 weeks transplantation,which demonstrated that carotid artery transplant from WISTAR to SD rat. Conclusion : Carotid arterial hemeotransplantation from Wistar to SD rat is a sucessful arterial allogaft model which can be used to study alloraft pathologic mechanism .Part II Expression of ET-1 ,ETA and ETB in Rat Arterial Allograft Objective : The study is investigate the expression of ET-1 ,ETA and ETB in the allograft carotid artery . Method : With the model of carotid arterial hemeotransplant from Wistar to SD rat , allograft artery was procured at post-operatively 1 week ,2 weeks and 4 weeks respectively .Graft arterial tissue ET-1 level was measured by radioimmunoassay .ET-1 ,ETA and ETB immunohistochemistry were performed . The pencentage of luman decrease was as evaluated as the grade of allograft intimal hyperplasia . Result : The tissue level of ET-1 in allograft artery was continouely increased after transplantation ,whereas ET-1 level was returned to normal in the syngene graft artery after 2 weeks transplanttation . The increasing expresssion of ETA in the intimal .medial can be seen and was associated with the index of intimal hyperplasia ,while changes of expression of ETB in the medial of allograft arterial tissue was not associated with intimal hyperplasia. Conclusion : ET-1 and ETA play significant roles in the process of allograft vasculopathy. Part III Inhibition of Intimal Hyperplasia in Allograft Artery with AS-ETA-ODN. Objective : The study is to investigate the inhibition of intimal hyperplasia in allograft artery with AS-ETA-ODN. Method : With high pressue technique , AS-ETA-ODN was transfected to the donor carotid artery before transplantation . Transfection efficacy was envaluned by the percent of flourence cell in the the arterial tissue. 1 and 4 weeks af