Azam Mohammed Ali, Wagg Cory S, Massé Stéphane, Farid Talha, Lai Patrick F H, Kusha Marjan, Asta John, Jaimes Rafael, Kuzmiak-Glancy Sarah, Kay Matthew W, Lopaschuk Gary D, Nanthakumar Kumaraswamy
The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto, Ontario, Canada;
The Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada; and.
Am J Physiol Heart Circ Physiol. 2015 Nov;309(9):H1543-53. doi: 10.1152/ajpheart.00404.2015. Epub 2015 Sep 4.
Ventricular fibrillation (VF) is an important cause of sudden cardiac arrest following myocardial infarction. Following resuscitation from VF, decreased cardiac contractile function is a common problem. During and following myocardial ischemia, decreased glucose oxidation, increased anaerobic glycolysis for cardiac energy production are harmful and energetically expensive. The objective of the present study is to determine the effects of dichloroacetate (DCA), a glucose oxidation stimulator, on cardiac contractile dysfunction following ischemia-induced VF. Male Sprague-Dawley rat hearts were Langendorff perfused in Tyrode's buffer. Once stabilized, hearts were subjected to 15 min of global ischemia and 5 min of aerobic reperfusion in the presence or absence of DCA. At the 6th min of reperfusion, VF was induced electrically, and terminated. Left ventricular (LV) pressure was measured using a balloon. Pretreatment with DCA significantly improved post-VF left ventricular developed pressure (LVDP) and dp/dtmax. In DCA-pretreated hearts, post-VF lactate production and pyruvate dehydrogenase (PDH) phosphorylation were significantly reduced, indicative of stimulated glucose oxidation, and inhibited anaerobic glycolysis by activation of PDH. Epicardial NADH fluorescence was increased during global ischemia above preischemic levels, but decreased below preischemia levels following VF, with no differences between nontreated controls and DCA-pretreated hearts, whereas DCA pretreatment increased NADH production in nonischemic hearts. With exogenous fatty acids (FA) added to the perfusion solution, DCA pretreatment also resulted in improvements in post-VF LVDP and dp/dtmax, indicating that the presence of exogenous FA did not affect the beneficial actions of DCA. In conclusion, enhancement of PDH activation by DCA mitigates cardiac contractile dysfunction following ischemia-induced VF.
室颤(VF)是心肌梗死后心脏骤停的重要原因。从室颤复苏后,心脏收缩功能下降是一个常见问题。在心肌缺血期间及之后,葡萄糖氧化减少,用于心脏能量产生的无氧糖酵解增加,这是有害的且能量消耗大。本研究的目的是确定葡萄糖氧化刺激剂二氯乙酸(DCA)对缺血诱导的室颤后心脏收缩功能障碍的影响。雄性Sprague-Dawley大鼠心脏在Tyrode缓冲液中进行Langendorff灌注。一旦稳定,心脏在有或没有DCA的情况下进行15分钟的全心缺血和5分钟的有氧再灌注。在再灌注第6分钟时,电诱导室颤并终止。使用球囊测量左心室(LV)压力。DCA预处理显著改善了室颤后左心室发展压力(LVDP)和dp/dtmax。在DCA预处理的心脏中,室颤后乳酸产生和丙酮酸脱氢酶(PDH)磷酸化显著降低,表明葡萄糖氧化受到刺激,并且通过激活PDH抑制了无氧糖酵解。全心缺血期间心外膜NADH荧光高于缺血前水平,但室颤后低于缺血前水平,未处理的对照组和DCA预处理的心脏之间无差异,而DCA预处理增加了非缺血心脏中NADH的产生。向灌注溶液中添加外源性脂肪酸(FA)后,DCA预处理也导致室颤后LVDP和dp/dtmax得到改善,表明外源性FA的存在不影响DCA的有益作用。总之,DCA增强PDH激活可减轻缺血诱导的室颤后心脏收缩功能障碍。