Effects of adenosine A_1 receptor agonist postconditioning on myocardial ischemia reperfusion injury in rabbits

Objective To investigate the protective effects of adenosine A1receptor agonist(2-chloro-N6-cyclopentyladenosine,CCPA) postconditioning on myocardial ischemia-reperfusion injury in rabbits.Methods Thirty-two New Zealand male white rabbits were randomly assigned to Sham group,IR group,ischemia group and CCPA group.Group sham was perfused for 160min,group IR was underwent 40min ischemia and 120min reperfusion;group ischemia was underwent three cycles of 30 seconds reperfusion and 30 seconds LAD re-occlusion immediately after 40min ischemia and before 120min reperfusion,and group CCPA was given CCPA 100μg/kg immediately after 40min ischemia in 1min and before 120min reperfusion.Blood samples were taken from arterial line at 20min before occlusion(T1),20min after occlusion(T2),40min after occlusion(T3),1h after reperfusion(T4) and 2h after reperfusion(T5) for determination of plasma cTnI.At the end of the reperfusion,infarct size(IS) and area at risk(AAR) were defined by Evans and TTC staining.Plasma superoxide dismutase(SOD) activity and malondialdhyde(MDA) were determined at the end of reperfusion.Results The levels of cTnI were significantly less during reperfusion in the 2 postconditioning groups than those in IR group.The plasma MDA content was significantly lower and SOD activity as significantly higher in the 2 postconditioning groups than those in I/R group,but there was no difference between the 2 postconditioning groups.Conclusion CCPA postconditioning is as effective as ischemic postconditioning in protecting myocardium against ischemia-reperfusion injury in rabbits.Decrease in oxygen free radicals and increase in antioxidant activity may be involved.