心肌ONOO- 改变对糖尿病大鼠缺血再灌注损伤及细胞凋亡的影响

 目的： 测定不同周期链脲佐菌素（STZ）诱导糖尿病大鼠心肌超氧亚硝酸根离子(ONOO-)改变及其对缺血/再灌注（I/R）损伤及细胞凋亡的影响。方法： 阻断和开放左冠状动脉前降支建立大鼠急性心肌I/R模型，用TTC染色，测定大鼠心肌I/R后梗死面积；用免疫印迹法定量分析代表心肌凋亡水平的半胱氨酸天冬氨酸蛋白酶3（caspase-3）的表达；形态测定（morphometric）法测定ONOO-生成的标志性产物硝基酪氨酸（NT）的水平。结果： 在STZ处理后2周糖尿病组(2WKD)心肌梗死面积35.00%±3.00%，明显小于相应周期对照组(2WKC)51.00%±3.30%，P<0.05；STZ 处理后16周糖尿病组(16WKD)，梗死面积61.00%±3.00%大于相应对照组(16WKC)50.00%±2.00%，P<0.05；在缺血再灌注后，caspase-3的表达,在 2WKD+I/R组（A值：481±77）小于2WKC+I/R组（A值：1 033±46），而16WKD+I/R 组（A值：1 206±78）caspase-3的表达高于16WKC+I/R 组（A值：940±72），P<0.05；硝基酪氨酸的水平在 2WKD 组（A值：211±13 ）明显低于2WKC组（A值：409±12），但在16WKD组（A值：506±37）则高于16WKC组（A值：378±46），P<0.05。结论： STZ诱导急、慢性期糖尿病对心肌I/R损伤和细胞凋亡的影响呈现相反的作用，这可能是由于急、慢性期糖尿病心肌相反的ONOO-水平而引起的。

Effects of diabetes on ischemic/reperfusion injury and cell apoptosis in rats myocardium via alterations in peroxynitrite

AIM: To determine the effects of different-term streptozotocin(STZ)-induced diabetes on ischemia/reperfusion (I/R) injury and cell apoptosis in rats myocardial via alterations in myocardial peroxynitrite.METHODS: The models of I/R injury were induced by occlusion and reperfusion of the left descending coronary artery (LDCA) in rats.I/R-induced infarct size was determined using triphenyltetrazolium chloride (TTC) staining.Quantified caspase-3 expression was used to represent apoptosis by Western blotting analysis.Peroxynitrite formation as indicated by nitrotyrosine level was measured by morphometric analysis.RESULTS: Two weeks after STZ treatment,infarct size (35.00%±3.00%) was smaller in 2 weeks diabetic hearts (2WKD) as compared with time-matched control group (2WKC) (51.00%±3.30%),whereas after 16 weeks of diabetes (16WKD),the infarct size (61.00%±3.00%) was bigger in the diabetic hearts as compared with the 16WKC group (50.00%±2.00%,P<0.05).After I/R,caspase-3 expression was lower in 2WKD+I/R group (A value：481±77) than that in 2WKC+I/R group (A value：1033±46),while caspase-3 was higher in the 16WKD+I/R group (A value：1206±78) than that in 16WKC+I/R group (A value：940±72,P<0.05).Nitrotyrosine was lower in 2WKD hearts (A value：211±13) than that in controls (A value：409±12),but was higher in 16WKD group (A value：506±37) compared with controls (A value：378±46,P<0.05).CONCLUSION: Short- and long-term STZ induced diabetes exerts opposite influences on myocardial I/R injury and cell apoptosis,and these contradictory influences may depend on different alterations in myocardial peroxynitrite.