Objective To observe the effect of moxibustion(Moxi)preconditioning with seed-sized moxa cones on myocardial ischemia-reperfusion injury(MI/RI)at different stages

and to analyze the correlation between this effect and the expression of autophagy related protein Beclin 1.Methods This study contains two parts:1)changes of myocardial pathological injury and percentages of myocardial infarcted area at different time-points after modeling and Moxi intervention

and 2)effect of Moxi on contents of serum cardiac troponin T(cTnT)and expression of myocardial Bcl-2

Bax and Beclin 1 proteins.In the first part

42 SD rats were randomly divided into model group

1 day(d)Moxi group

2 dMoxi group

3 dMoxi group

4 dMoxi group

5 dMoxi group and 7 dMoxi group.The model of MI/RI was established by ligating the left anterior descending coronary artery(LAD)for 30 min and reperfusion for 240 min.The electrocardiogram(ECG)of standard limb lead Ⅱ was monitored and the heart was taken 4 hafter reperfusion for examining myocardial infarcted size with triphenyl tetrazolium chloride(TTC)staining.In the second part

48 SD rats were randomized into sham-operation

model

moxibustion and autophagy inhibitor(3-MA)groups

with 12 rats in each group.The serum cTnT level was assayed and histopathological changes of the myocardial tissue below the ligation site were examined with HE staining

and the expression levels of Bcl-2

Bax and Beclin 1 proteins in the myocardial tissue below the LAD-ligated site were detected using Western blot.Results Compared with the model group

the percentages of myocardial infarcted area were significantly decreased in the 4 d

5 dand 7 dMoxi groups(P<0.05)

but without significant differences among the 3 Moxi groups(P>0.05).The state of MI-induced breakage and disordered arrangement of myocardial fibers with interstitial edema and inflammatory cell infiltration at the MI stage in the Moxi group and at the reperfusion stage in the autophagy inhibitor group was relatively lighter.The levels of serum cTnT content and Bax/Bcl-2 and Beclin 1 protein expression at the MI and reperfusion stages were significantly higher in the model group than in the sham-operation group(P<0.01)

and considerably lower in the Moxi and autophagy groups than in the model group(P<0.01).The serum cTnT content

ratio of Bax/Bcl-2 expression and Beclin 1 expression levels at the MI and reperfusion stages were significantly lower in the autophagy inhibitor group than in the Moxi group(P<0.05).Conclusion Moxibustion with seed-sized moxa cones at"Neiguan"(PC 6)can effectively alleviate myocardial ischemia in MI/RI rats

which is probably related to its effect in down-regulating Bax/Bcl-2 and Beclin 1 expression and in inhibiting autophagy.