Abstract: Objective To explore the effect of xanthine oxidase inhibitors allopurinol on collagen remodeling in non-infarcted myocardium after myocardial infarction in rats．Methods Myocardial infarction models were produced by ligation of anterior descending coronary artery．The survivals were randomly divided into 3 groups：sham operation group, MI group and allopurinol group(50 mg/kg)．On the 7th , 14th , 21st and 28th day respectively , the collagen content were detected．The type Ⅰ and type Ⅲ collagen volume fraction(CVF) and Ⅰ/Ⅲ ratio in non-infarcted zones(NIZ) were examined with PSR staining and the mRNA expressions were detected with RT-PCR, the activities of xanthine oxidase(XO) and O2.-，.OH-scavenging in NIZ were examined by colorimetry．In addition, the expression of XO protein by Western blotting analysis and pathological change in LV were detected on the 28th day．Results Compared with sham group，the mRNA expressions, CVF of typeⅠand type Ⅲ collagen in NIZ were increased in MI group．The typeⅠ/Ⅲ ratio in NIZ was increased after decreased．The collagen content and activity of XO were boosted but the activities of O2.-, .OH-scavenging were decreased(P <0.05 or P <0.01)．Compared with MI group, the changes of these parameters above were alleviated in allopurinol group．There were no significant difference in infarct size and XO expression between allopurinol and MI group．Conclusion Allopurinol could attenuate the myocardial collagen deposition and typeⅠ/Ⅲ ratio in NIZ to improve myocardial collagen remodeling in rats after MI．

Key words: allopurinol, xanthine oxidase, reactive oxygen species, collagen remodeling, myocardial infarction