Objective To explore the effect of xanthine oxidase inhibitor allopurinol on cardiomyocyte apoptosis in rats after myocardial infarction (MI).  Methods MI model was established by the ligation of anterior descending coronary artery. The survivors were randomly divided into 3 groups: sham operation group (n=5)

MI group (n=16) and allopurinol group (n=15

receiving allopurinol 50 mg·kg

-1

· d

-1

). After 28 days

the infarct size was measured. In noninfarcted zone (NIZ)

cardiomyocyte apoptosis was detected by TUNEL; the expression of Fas was detected by immunohistochemistry; the expressions of xanthine oxidase (XO) and caspase 3 were detected by Wester

n blot. In addition

the activities of XO and ·O

2

-

·OH-scavenging in NIZ were detected by colorimetry.  Results Compared with sham operation group

the apoptosis index and expressions of Fas

XO

caspase 3 in NIZ were significantly increased in MI group. The activity of XO was increased but the activities of ·O

2

-

and ·OH-scavenging were decreased (P0.01). Compared with MI group

the changes of these parameters above were alleviated in allopurinol group. There was no significant difference in infarct size and XO expression between allopurinol and MI groups (P0.05).  Conclusion Allopurinol could inhibit the cardiomyocyte apoptosis in NIZ in rats. The protective mechanism of allopurinol involves the reduction of reactive oxygen species and depression of the expressions of Fas and caspase 3.