Low-dose β-Ray Inhibits Intimal Hyperplasia And Stenosis Of Autologous Vein Grafts In Rabbit Model

Coronary artery bypass graft is one of the most important method of coronary artery revasculization. Saphenous vein continues to be the most commonly used conduit. But its stenosis or occlusion resulted from intimal hyperplasia detracts the result seriously and remains to be solved.Intimal hyperplasia and stenosis is a complex process resulted from many factors mainly proliferation of intimal smooth muscle cells (SMC),secretion of extracellular matrix and subsequent vessel remodeling. But its exact mechanism is still unknown. Regulation of cell cycle is the last link of the series of messager conduction of cell proliferation. G₁-S stage is the most important because the duration of cell proliferation cycle is mainly depend upon the duration of G₁ stage and once the cells advanced into the S stage from G₁ stage, the proliferation will finish automatically without depending of the extracellular messages. The synthesis and degradation of the extracellular matrix take part in the proliferation and migration of SMC on the one hand and join the vascular remodeling on the other hand, but its effect on the SMC proliferation and stenosis of autologous vein grafts(AVG) is unclear. A lot of methods have been tried to prevent the intimal hyperplasia and stenosis of AVG. Drug therapy can improve the early patency rat but has no later effect. Mechanical method is unstatisfactory also. Althought gene therapy has broad prospects, a lot of works have to be done before it can be implied in clinical practice. In recent years radiotherapy has been used to prevent artery restenosis post-PTA and PTCA and the result are excellent, but research work of its effect on AVG is rare.Objective 1.To establish the rabbit model of AVG and observe the microscopic and ultrastructure of proliferation of intimal SMC of grafts. 2.To observe the change trend of type I,III collagen and elastin of vein grafts post-implantation and its correlation with AVG cavities lose. 3.To observe the expression of the cell cycle regulating genes P₁₆, P₂₁ and cyclin D₁ in AVG and its relation with proliferation of SMC. 4.To compare the effects of low-dose ³²P with different doses and different radiation methods on the intimal hyperplasia of AVG to select the best dose and compare its effect with that of angiotensin converting enzyme inhibitor Cartopril.Materials and Method 1.With the "Cuff" technique, the external jugular vein of New Zealand rabbit was implanted into the external carotid of common side. Morphological changes of the SMC were observed under light microscape and...