| Objective:To investigate the effect of NADPH oxidase on ventricular remodeling after myocardial infarction(MI) in rats.Methods: Sprague-Dawley rats weighing 150～220g were divided into the operated (O) group and the sham-operated (S) group by ligation of the anterior descending coronary artery or without ligation. Every group was randomly divided into two subgroups, NADPH oxidase inhibitor apocynin (15mg/kg/d,A) and equivalent placebo(P) was used to intragastric administration for five weeks since the second day after operated.All rats were sacrificed on the 6th week after surgery respectively, the body weight(BW) and the left ventricular ejection fraction (LVEF) by echocardiography were acquired before operated and sacrificed. Hearts were taken out after rats were sacrificed and the hart weight (HW),the left ventricular weight (LVW) were weighed,the collagen I content and the collagen III content in the non-infarcted area in left ventricular were measured by ELISA method,the cardiac myocyte apoptosis index in the non-infarcted area was got by TUNEL method ,and the correlation between non-infarcted area cardiac myocyte apoptosis index and LVEF was observed.Results:1. 86 male SD rats were used in experiment,6 rats in the sham-operated group (SP),6 rats in the sham-operated + treated group(SA),7 rats in the myocardial infarction group (OP),6 rats in the myocardial infarction + treated group(OA) were acquired finaly.2. BW in SP,OP,SA and OA were(314.17±20.67)g,(296.71±36.63) g,(298.00±57.06) g and (329.83±24.64)g, the differences were no statistical significance among them. HW in SP and SA were (646.17±85.44)mg and (648.67±63.11)mg ,the difference was no statistical significance between them ;it in OP and OA were (1144.14±59.46)mg and(884.00±97.14)mg ,the differences were statistical significance compared with SA and SP (p<0.05);there was statistical difference between OA and OP (p<0.05). the heart weight index(HWI) in SP and SA were(2.07±0.31)mg/g and(1.98±0.30)mg/g,the difference was no statistical significance between them ;it in OP and OA were (3.91±0.47) mg/g and (3.02±0.35)mg/g, the differences were statistical significance compared with SA and SP (p<0.05); there was statistical difference between OA and OP(p<0.05). LVW in SP and SA were (418.33±35.75) mg and(435.83±74.85)mg,the difference was no statistical significance between them ; it in OP and OA were (746.86±53.09) mg and(561.17±81.29)mg, there were statistical difference compared with SA and SP (p<0.05); there was statistical difference between OA and OP(p<0.05). the left ventricle weight index(LVWI)in SP and SA were(1.34±0.19)mg/g和(1.33±0.32)mg/g,the difference was no statistical significance between them ; it in OP and OA were (2.55±0.34) mg/g and(1.91±0.22)mg/g, there were statistical differences compared with SA and SP (p<0.05); there was statistical difference between OA and OP too(p<0.05).3,LVEF in SP and SA were (78.58±5.03) % and(73.84±5.48)% , there was no significant difference between them;it in OP and OA were(37.80±3.68)% and (47.34±7.35)%, the differences were statistical significance compared with SA and SP (p<0.01); the difference was statistical significance between OA and OP too(p<0.01).4. The non-infarcted area collagen I content of cardiac muscle tissue in SP and SA were (331.35±94.43) ng/mg and (322.44±78.32), the difference was no statistical significance beween them; it in OP was(499.91±44.36)ng/mg,there were significant differences compared with SA and SP (p<0.01);it in OA was(361.17±26.41)ng/mg, differences were no statistical significance compared with SA and SP, there was statistical significance between OA and OP (p<0.01). The non-infarcted area collagen III content of cardiac muscle tissue in SP,OP,OA and SA were (37.83±5.80) ng/mg,(35.55±2.88)ng/ mg,(35.14±4.59)ng/mg and(36.94±3.21) ng/mg, there were no statistical significances among them. the non-infarcted area collagen I/III ratio of cardiac muscle tissue in SP and SA were (8.77±2.47) and SA(9.21±2.83), the difference was no statistical significance between them ; it in OA was(10.43±1.43), there were no statistical significance compared with SA and SP; it in OP was(14.19±2.04), there were significant differences compared with SA and SP (p<0.01); there was significant difference between OA and OP too(p<0.01).5. The non-infarcted area cardiac myocyte apoptosis index in SP and SA were(0.33±0.21)% and(0.42±0.15)%, there was no statistical difference between them;it in OP and OA were(4.97±1.33)% and(2.46±1.43)%, there were significantly increased in the non-infarcted area cardiac myocyte apoptosis index compared with SA and SP (p<0.01) ; difference was statistical significance between OA and OP(p<0.01).6. The non-infarcted area cardiac myocyte apoptosis index was negatively correlation with the LVEF (r=-0.757,p<0.01).Conclusion: 1. HWI and LVWI in the myocardial infarction group were higher than these in the sham-operated group, these indexs decreased in the myocardial infarction + treated group,it demonstrats that NADPH oxidase is one of factors promote myocardial compensatory hypertrophy after MI.2. Collagen I content,the collagen I/III ratio of cardiac muscle tissue in the non-infarcted area in the myocardial infarction group increased significantly compared with the sham-operated group;but these in the myocardial infarction + treated group decreased significantly compared with the myocardial infarction group and equivalent with the sham-operated group .It indicates that NADPH oxidase plays a critical role in the process of interstitial fibrosis post-MI.3. The non-infarcted area cardiac myocyte apoptosis index in the myocardial infarction group increased significantly compared with the sham-operated group, it decreased significantly in the myocardial infarction + treated group. It indicates that NADPH oxidase plays an important role in the non-infarcted area cardiac myocyte apoptosis. There is negative correlation between the non-infarcted area cardiac myocyte apoptosis index and LVEF, it indicats that the non-infarcted area cardiac myocyte apoptosis is important cause of LVEF decreasing post-MI.
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