Objective:To investigate the protection mechanism of adenosine A1 receptor agonist(2-chloro-N6-cyclopentyladenosine

CCPA)delayed preconditioning for rabbit myocardium during ischemia reperfusion.Methods:Thirty New Zealand male white rabbits were randomly assigned to Sham group

I/R group and CCPA group

with ten in each.Group CCPA was given CCPA 0.1 mg/kg before myocardial ischemia.Twenty-four hours later the I/R and CCPA underwent 40 min of coronary occlusion followed by 2 h of reperfusion.Blood samples were taken from arterial line at 20 min before occlusion(T)1

20 min after occlusion(T2)

40 min after occlusion(T)3

1 h after reperfusion(T)4and 2 h after reperfusion(T)5for determination of the plasma levels of IL-10.At the end of the reperfusion

infarct size(IS)and area at risk(AAR)were defined by Evans blue and TTC staining.The heart was harvested and levels of the HSP70 were determined by Western blot analysis

and ultrastructures were observed under the electron microscopy.Results:The IL-10 and HSP70 levels of group CCPA was higher than those of group I/R.The CCPA(P<0.05)reduced infarct size(22.1%±3.8%)of the left ventricular area at risk compared with the I/R(41.8%±4.3%)(P<0.05).The injury of group I/R was severer than that of group CCPA under the light microscope.Conclusion:CCPA can increase the levels of HSP70 and IL-10 during ischemia-reperfusion

which maybe the molecular mechanism of CCPA delayed preconditioning on cardioprotection.