容量负荷导致的心肌重构过程中心肌能量代谢模式的转化

Transformation of Myocardial Energy Metabolism Pattern during Myocardial Remodeling Caused by Volume Overload

目的阐明心肌结构重塑过程中能量代谢模式的转化特征。方法C57/BL6小鼠30只,20~30 g,雌雄各半,随机分为模型组和假手术组(n=15)。实验动物接受3%水合氯醛(3 ml/kg)腹腔注射麻醉,模型组动物无菌游离腹主动脉和下腔静脉,并吻合,建立心肌结构重构模型。分别采集不同组别实验动物心肌组织,检测不同途径能量代谢关键酶的蛋白表达水平,初步判断不同疾病阶段,心肌能量代谢模式。然后利用三磷酸腺苷(ATP)检测试剂盒测定不同组别心肌细胞ATP产量,并利用TUNEL方法测定不同组别心肌细胞凋亡水平差异。结果与假手术组相比,模型组实验动物在术后2周时脂肪酸β氧化途径关键酶肌型肉碱棕榈酰转移酶-I(MCPT-1)、中链脂酰辅酶a脱氢酶(MCAD)、过氧化物酶体增殖物激活受体a(PPARα),以及糖代谢关键酶丙酮酸激酶(PK)无明显变化。但在术后5周时,MCPT-1、MCAD、PPARα均表现出不同程度的下降,PK有升高趋势,但未达显著差异水平,但心肌组织ATP含量明显下降,心肌细胞凋亡指数(AI)显著升高。术后15周时,MCPT-1(MCPT-1 vs GAPDH:0.5 vs 0.85,P<0.05)和MCAD(MCAD vs GAPDH:0.6 vs 1.25,P<0.05)表达量显著下降,PPARα水平(PPARαvs GAPDH:0.4 vs 1.2,P<0.01)非常显著下降,而PK水平(PK vs GAPDH:0.53 vs 0.92,P<0.01)明显升高。心肌细胞ATP含量明显降低,心肌细胞凋亡指数明显升高。结论亚急性期和代偿期心肌细胞的代谢模式以脂肪酸β氧化为主,而在失代偿期脂肪酸beta氧化障碍,向糖酵解代谢模式转换,说明结构重塑心肌向胚胎型模式转变,这可能(至少部分)是心肌细胞产能能力下降及心肌细胞凋亡水平升高的原因。

Objective To elucidate the transformation of energy metabolism patterns in the process of myocardial remodeling induced by volume overload.Methods Thirty C57/BL6 mice,20-30 g,15 males and 15 females,were randomly divided into model group and sham operation group(n=15).Experimental animals in the model group received 3%chloral hydrate(3 ml/kg)intraperitoneally for anesthesia.Then abdominal aorta and inferior vena cava were aseptically separated and anastomosed to establish a myocardial structural remodeling model.Animals in the sham operation group were only isolated from blood vessels without anastomosis.Myocardial tissues from different groups of experimental animals were collected,and the protein expression levels of key enzymes in different energy metabolism pathways were detected using Western blot.Then,the Adenosine triphosphate(ATP)detection kit was used to determine the ATP production,and the TUNEL method was used to determine the cell apoptosis level in different groups.Result Compared with sham operation group,the muscle carnitine palmitoyl transferase-I(MCPT-1),medium chain acyl coenzyme A dehydrogenase(MCAD),peroxisome proliferator-activated receptor a(PPARα)and pyruvate kinase(PK)did not change significantly.However,at 5 weeks after surgery,MCPT-1,MCAD and PPARαall showed varying degrees of decline,and PK increased,but no significant differences were found.ATP production of myocardial tissue decreased significantly,and the cardiomyocyte apoptosis index(AI)increased significantly.At 15weeks after surgery,the expression of MCPT-1(fold of GAPDH 0.5 vs 0.85,P<0.05)and MCAD(fold of GAPDH,0.6 vs 1.25,P<0.05)decreased significantly,meanwhile,the levels of PPARαdecreased(fold of GAPDH,0.4 vs 1.2,P<0.01)and pyruvate kinase increased significantly(0.53 vs0.92,P<0.01).The ATP production of cardiomyocytes decreased significantly,and the apoptosis index of cardiomyocytes increased significantly.Conclusion The metabolic pattern of cardiomyocytes in the subacute and compensatory stages is dominated by fatty acid beta oxidation,while during the decompensation phase,myocardia metabolic pattern shifts from fatty acid beta oxidation to glycolytic metabolism,suggesting that structural remodeling induces myocardial regression to"embryonic metabolic pattern".This may be(at least in part)the reason for the decreased ATP production capacity of cardiomyocytes and the increased level of cardiomyocyte apoptosis.