Objective    To investigate the effect of cerebral ischemia on the cognitive function of rats with Alzheimer’s disease(AD)  and the role of cerebral ischemia in progression of cognitive damage of AD.     Methods    The male SD rats were divided randomly into 4 groups: the control group

the ischemia group

the AD group and the ischemia plus AD group. endothelin-1(ET-1) injections was given to ischemia group into the right striatum; β

1-40

injections to AD group in the right dentate gyrus

and both ET-1 and Aβ

1-40

injections to the ischemia plus group.  The cognitive functions of the 4 groups of rats was detected by Morris wat

er maze and shuttle box.     Results    The AAR％ and PAR％ of AD plus cerebral ischemia group were the lowest in the four groups in shuttle box experiment (P0.01

P0.05)

followed by the AD group and the control group.  In navigation test of Morris water maze

the average escape latency of AD plus cerebral ischemia group was the longest in the four groups (P0.01). In spatial probe test of Morris water maze

the initial time taken to reach the hidden prior platform of AD plus cerebral ischemia group was the longest （P0.01) and its frequency passing through the prior platform was the lowest(P0.01)

followed by the AD group and the control group.     Conclusions    The cognitive function of rats in the AD group decreased significantly after cerebral ischemia

which aggravated the cognitive damage of AD.