Objective. The experiment was designed to study the association of cerebral ischemia and reperfusion with endothelin- 1 （ET- 1） gene expression of rat brains and time-dependent changes of ET- 1 gene expression during cerebral ischemia.Materials and methods. Thirty- three male SD rats were divided into dot blot hybridization（n = 27） and in silu hybridization groups（n= 6）. The focal cerebral ischemia and reperfusion models were made with suture embolism of middle cerebral artery. Dot blot hybridization groups were redivided into control and ischemic subgroups （ischemia for 0. 5

1

1. 5

3

6

12

24

48 and 72 h respectively）. In situ hybridization groups were redivided into ischemia and reperfusion groups. After 24 h ischemia and 24 h reperfusion

ET1 gene expressions were investigated with in situ hybridization and the resuhs were analyzed with IBAS 2000 Image Analysis System.Results. Dot blot hybridization showed that ET-1 mRNA of cerebral cortex and caudate- putamen was increased at 6 h of ischemia and reached peak at 24 h （3. 9 and 3. 7 fold respectively）

and at 72 h of ischemia it remained at high levels（3. 5 and 2. 1 fold respectively）. In silu hybridization showed that the levels of ET- 1 mRNA of cerebral cortex and caudate-putamen were also markedly increased both in 24 h ischemia and 24 h reperfusion groups （P<0. 01

P<0. 05 respectively） .Conclusions. ET-1 gene expression in focal ischemic brain tissue were markedly and progressively increased during cerebral ischemia and reperfusion and downregulation of ET- 1 gene expression may be a new approach to the treatment of ischemic cerebrovascular diseases.