内毒素血症心功能不全的脂肪酸代谢紊乱机制的初步研究

A PRELIMINARY INVESTIGATION ON THE MECHANISMS OF FATTY ACID METABOLISM DISORDER IN ENDOTOXEMIA RATS WITH HEART FAILURE

目的明确内毒素血症中心脏功能改变和可能涉及的脂肪酸代谢途径变化的机制,探讨AMPK(单磷酸腺苷活化蛋白激酶AMP-activated protein kinase)及下游靶点在心肌组织能量贮存与消耗调节中的作用。方法 SD大鼠尾静脉注射LPS(5mg/kg)建立内毒素血症模型,12h后麻醉,经颈总动脉置管监测心功能:左心室内压(LVSP)、左心室舒张末压(LVEDP)、左心室压力上升/下降最大速率(±dp/dtmax),进行心肌和血清游离脂肪酸检测,应用western blot方法测定AMPKα,p-AMPKα,肌型-肉毒碱脂酰转移酶1(muscle carnitine pamitoyltransferase1,m-CPT1),乙酰辅酶A羧化酶(acety1 coenzyme A carboxylase,ACCase),p-ACCase蛋白变化。结果内毒素血症组(LPS组)大鼠在注射LPS 12h后,+dp/dtmax,-dp/dtmax,和LVSP与正常对照组相比明显降低,而LVEDP则明显上升。内毒素血症组血清及心肌游离脂肪酸均高于正常组。两组之间AMPKα和ACCase蛋白表达无显著差异,而p-AMPKα和p-ACCase表达在内毒素血症大鼠组中明显增高,同时m-CPT1蛋白表达明显下降。结论内毒素血症心肌损伤与脂肪酸代谢紊乱有关,涉及到m-CPT1,p-ACCase和p-AMPKα蛋白表达的变化。

Objective To determine the changes in cardiac function and possible mechanisms involved in fatty acid metabolic pathways in endotoxemia and to explore the role of adenosinemonophosphate-activated protein kinase （AMPK） and the downstream targets in the regulation of energy storage and consumption in myocardial tissue. Methds Animal model of endotoxemia was induced by tail vein injection of lipopolysaccharide （LPS） in 6 Wistar rats, while normal control model was injected with saline （n=6）. Cardiac function parameters, such as left ventricular pressure （LVSP）, left ventricular end-diastolic pressure （LVEDP）, and left ventricular pressure rise/fall maximum rate （4- dp/dtmax）, were observed 12 hours after LPS injection. Blood was taken and serum and cardiac free fatty acids levels were also measured. The protein expression of AMPKα, phosphorylated-AMPKα （p-AMPKα）, muscle type - carnitine acyl transferase enzyme 1, muscle carnitine pamitoyltrans- ferasel （m-CPT1）, acetyl coenzyme A carboxylase acetyl coenzyme A carboxylase （ACCase） and phosphorylated-ACCase （p-ACCase） were assessed by Western blot. Results Compared with control group, ＋dp/dtmax, -dp / dtmax and LVSP decreased in endotoxemia group （LPS group） 12h after injection of LPS, while LVEDP increased significantly. In endotoxemia group, the levels of free-fatty acids in serum and myocardial were higher than those in the control group. Compared with control group, no significant difference was found in AMPKα and ACCase protein expression in LPS group, while p-AMPKα, p-ACCase protein expression in cardiac muscle were higher in LPS group than those in the control group. However, m-CPT1 protein expression was significantly decreased than that in the control group. Conclusion Myocardial injury in endotoxemia model is related to fatty acid metabolism disorder, and the alterations of m-CPT1, p-ACCase and p-AMPKα protein expression are also involved.