间歇性低氧在大鼠心肌缺血/再灌注损伤中的保护机制

Protection mechanism of intermittent hypoxia on heart ischemia/reperfusion injury in rats

目的研究磷脂酰肌醇3-激酶(PI3K)、低氧诱导因子(HIF-1α)、血管内皮生长因子2(VEGF-2)在间歇性低氧对大鼠心肌缺血/再灌注(I/R)损伤中的表达及保护机制。方法选取72只大鼠随机分为假手术组(n=18)、I/R+间歇性低氧(I/R+IH)组(n=18)、I/R组(n=18)、I/R+IH+磷脂酰肌醇3-激酶抑制剂组(I/R+IH+PI3K抑制剂组)(n=18),将大鼠暴露于低氧循环制作间隙性低氧动物模型,采用球囊结扎冠脉方法制作心肌缺血/再灌注动物模型。通过试剂盒检测心肌组织丙二醛(MDA)、谷胱甘肽(GSH)、肌酸激酶同工酶(CK-MB)含量,通过超声心动图监测大鼠舒张末期容积、收缩末期容积、左心室射血分数,通过Western blot法检测蛋白激酶B(AKt)、HIF-1α、VEGF-2表达。结果与假手术组比较,I/R组的MDA、CK-MB高于假手术组,GSH低于假手术组,左心室舒张末期容积及收缩期末期容积高于假手术组,左心室射血分数低于假手术组,AKt蛋白及HIF-1α、VEGF-2表达低于假手术组,差异有统计学意义(P<0.05)。I/R+IH组反映氧化损伤的MDA、CK-MB低于I/R组,GSH高于I/R组;左心室舒张末期容积及收缩期末期容积低于I/R组,左心室射血分数高于I/R组,AKt蛋白及HIF-1α、VEGF-2表达高于I/R组,差异有统计学意义(P<0.05)。I/R+IH+PI3K抑制剂组的MDA、CK-MB高于I/R+IH组,GSH低于I/R+IH组;左心室舒张末期容积及收缩期末期容积高于I/R+IH组,左心室射血分数低于I/R+IH组,AKt、HIF-1α、VEGF-2蛋白表达低于I/R+IH组,差异均有统计学意义(P<0.05)。结论 IH在心肌缺血损伤中具有心脏保护作用,其保护机制与激活磷脂酰肌醇酯3-激酶信号通路及促进HIF-1α、VEGF-2表达有关。

Objective To study the expression of phosphatidylinositide 3-kinase signaling pathway （PI3K）.hypoxia-inducible factor l α （HIF-lα,vaseular endothelial growth Factor-2 （VEGF-2） and to studied the correlation protection mechanism of intermittent hypoxia on heart ischemia/repeffusion （I/R） injury in rats.Methods 72 rats were randomly divided into the sham-operated group （n=l 8）,the myocardial I/R group （n=l 8）,the myocardial I/R＋intermittent hypoxia （IH） group （I/R＋ IH） （n=lS） and the myocardial I/R＋IH＋phosphatidylinositide 3-kinase （PI3K） inhibitor （wortmannin） group 0H＋I/R＋ PI3K inhibitor group） （n=18）.Mice were exposed to cycles to establish the IH model.l/R model was established by ligat- ing the left anterior descending coronary artery.The MDA and GSH of cardic muscle tissues,and the serum biomarkers CK-MB in the four groups were detected.The LV end-diastolic volume （LVEDV）,LV end-systolic （LVESV）,LV ejection fraction （LVEF） of the rats by echocardiography after 8 weeks were assessed.The expression of phosphorylation of protein kinase B （Akt）,HIF-Ic~,VEGF-2 was analyzed by Westen -blot.Results The level of MDA,CK-MB,LVEDV,LVESV of the I/R group was higher than that of the sham-operated group,the value of GSH,LVEF and the expression of AKt,ItIF-1α,VEGF-2 of the I/R group was lower than that of the sham-operated group,with significant difference （P〈0.05）.Thelevel of MDA,CK-MB,LVEDV,LVESV of the I/R＋IH group was lower than that of the I/R group,the value of GSH,LVEF and the expression of AKt,HIF-lc~,VEGF-2 of the I/R＋IH group was higher than that of the I/R group,with significant difference （P〈0.05）.The level of MDA,CK-MB,LVEDV,LVESV of the I/R＋IH＋PI3K inhibitor group was high- er than that of the sham-operated group,the value of GSH,LVEF and the expression of AKt,HIF-loL,VEGF-2 of the I/R＋ IH＋PI3K inhibitor group was lower than that of the sham-operated group,with significant difference （P〈0.05）.Conclusion The PI3K/Akt pathway and the expression of HIF-lα,VEGF-2 is important for IH-induced cardioprotection and may represent aviable target to reduce myocardial I/R injury.