Objective        To assess the value of myocardial contrast echocardiography（MCE）for  the myocardial perfusion of acute rejection in rats following heart transplantation.       Methods       Twenty-three male Brown Norway rats aged 12-15 weeks with a BMI of 143±23 g were used as allograft donors

and 53 male Lewis rats aged 12-15 weeks with a BMI of 158±19 g were used as allograft recipients (n=23)

isograft donors (n=15) and recipients (n=15) in this study. Rat heart transplantation models were established by transplanting allograft in 23 rats and by transplanting isograft in 15 rats. Thirty established transplanted rats were divided into 3 groups on days 2

4 and 6 with 6  allografts and 4 isografts in each

and then underwent MCE. Automatic fitting curve was plotted. A

β and A×β values were compared among 3 groups and between allograft and isograft transplantation groups.       Results      The rat heart transplantation models were successfully established in 18 allograft rats and in 12 isograft rats. The A

β and A×β values were significantly lower in allograft transplantation group on day 6 after transplantation (15.87±4.20

0.320±0.019

4.974±1.355

P0.05，P0.01) and in isograft transplantation group on day 2 than on days 4 and 6 after transplantation (21.71±0.017

0.365±0.013

7.908±0.374

P0.05). A significant difference was found in the A and β values between allograft and isograft transplantation groups on day 6 after transplantation (P0.05) and the A×β value was significantly different on day 4

especially on day 6

after transplantation (P0.05

P0.01).       Conclusion      MCE can show the gradually decreasing myocardial perfusion characteristics of ischemia/reperfusion and acute rejection in rats following heart transplantation

and can thus be used in the diagnosis and monitoring of acute rejection

in which the A×β value is a rather sensitive index.