Stanley W C, Hernandez L A, Spires D, Bringas J, Wallace S, McCormack J G
Syntex Discovery Research, Palo Alto, California, USA.
J Mol Cell Cardiol. 1996 May;28(5):905-14. doi: 10.1006/jmcc.1996.0085.
The purposes of this study were to: (1) assess myocardial pyruvate dehydrogenase (PDH) activity and substrate exchange under well-perfused and ischemic conditions; (2) determine the metabolic effects of an intra-coronary infusion of the PDH activator, dichloroacetate (DCA); and (3) measure the effects of ischemia and DCA on malonyl CoA levels. Experiments were performed in anesthetised open-chest swine under non-ischemic conditions, followed by 40 min with a 60% reduction in left anterior descending coronary artery (LAD) blood flow. Myocardial needle biopsies for measurement of PDH activity were taken after an intracoronary infusion of either saline or DCA (1 mM in LAD blood) under aerobic conditions, and after 37 min of ischemia. Pyruvate dehydrogenase activity was measured with and without maximal activation by swine PDH phosphatase. Malonyl CoA and acetyl CoA were measured after 40 min of LAD ischemia in myocardium from the ischemic DCA- or saline-treated LAD bed, and the non-ischemic untreated left circumflex coronary artery (CFX) perfusion bed. Net glucose, lactate and free fatty acid (FFA) uptakes were measured across the LAD perfusion bed throughout the study. Dichloroacetate treatment increased the amount of active dephosphorylated PDH to 88% of the total activity under aerobic conditions, compared to 55% with saline (P < 0.01). Ischemia did not significantly change PDH activation state in either group. Acetyl CoA and malonyl CoA contents were significantly elevated in ischemic DCA-treated myocardium compared to saline-treated ischemic myocardium. Dichloroacetate treatment significantly lowered rates of myocardial FFA uptake under both aerobic and ischemic conditions, but did not effect glucose uptake or lactate exchange. Free fatty acid uptake was negatively correlated to malonyl CoA levels (r = -0.68) during ischemia. It is proposed that the inhibition of FFA uptake observed with DCA in ischemic myocardium is due to malonyl CoA inhibition of carnitine palmitoyl transferase I.
（1）评估在灌注良好和缺血条件下心肌丙酮酸脱氢酶（PDH）的活性及底物交换；（2）确定冠状动脉内输注PDH激活剂二氯乙酸盐（DCA）的代谢效应；（3）测量缺血和DCA对丙二酰辅酶A水平的影响。实验在麻醉开胸猪身上进行，先在非缺血条件下进行，随后左前降支冠状动脉（LAD）血流减少60%持续40分钟。在有氧条件下冠状动脉内输注生理盐水或DCA（LAD血液中浓度为1 mM）后，以及缺血37分钟后，取心肌穿刺活检样本测量PDH活性。在有和没有猪PDH磷酸酶最大激活的情况下测量丙酮酸脱氢酶活性。在LAD缺血40分钟后，测量缺血DCA或生理盐水处理的LAD床心肌以及非缺血未处理的左旋冠状动脉（CFX）灌注床心肌中的丙二酰辅酶A和乙酰辅酶A。在整个研究过程中，测量通过LAD灌注床的净葡萄糖、乳酸和游离脂肪酸（FFA）摄取量。与生理盐水组（55%）相比，DCA处理使有氧条件下活性去磷酸化PDH的量增加到总活性的88%（P<0.01）。缺血在两组中均未显著改变PDH的激活状态。与生理盐水处理的缺血心肌相比，缺血DCA处理的心肌中乙酰辅酶A和丙二酰辅酶A含量显著升高。DCA处理在有氧和缺血条件下均显著降低心肌FFA摄取率，但不影响葡萄糖摄取或乳酸交换。缺血期间，FFA摄取与丙二酰辅酶A水平呈负相关（r=-0.68）。有人提出，在缺血心肌中观察到的DCA对FFA摄取的抑制作用是由于丙二酰辅酶A对肉碱棕榈酰转移酶I的抑制。
