Objective: To establish an arterial restenotic model

and to study the pathogenesis of restenosis after angioplasty. Methods: The balloon catheter injury was performed on left common carotidartery of rat by imitating the process of angioplasty. The process of neointimal and media hyperplasia was observed and the proliferation index of vascular smooth muscle cell (VSMC) at different time after operation was measured. The change of phenotype of VSMC in injured arteries was also surveyed with electron microscope. Results: Arterial neointima hyperplasia occurred after injury and reached to summit at 14 to 28 d. Cell proliferation attained a maximum at 4 day in the media (43.92%) and at 9day in the intima (63.98%). Immunostain of CD68 was negative whereas α-actin was mostly positive in the neointimal and medial cells. Ultrastructurally

the bulk of cytoplasm of VSMCs was filled with organelles with scattered myofilaments peripherally located. Conclusion:Neointima hyperplasia occurs after balloon injury and results in lumen stenosis. VSMC phenotype transformation

proliferation

migration

and extracellular matrix production are the key celllaur processes in this lesion.