FATTY ACID METABOLISM IN CARDIAC ISCHEMIA

本提案将研究脂肪酸氧化的细胞调控 (FAO)缺血心脏和培养的新生大鼠心肌细胞。的 乙酰辅酶A羧化酶（C-ACC）心脏亚型在 丙二酰辅酶A的细胞质合成和随后的抑制 肉毒碱棕榈酰转移酶I（CPT-I）未知。乳酸盐可能影响 C-ACC在脑缺血及早期调控FAO表达 再灌注，其中组织乳酸盐升高的条件。瞬态 在缺血过程中，通过产生乳酸激活C-ACC可能 将氧化代谢转移到碳水化合物的使用， 早期再灌注期间条件占主导地位。脂肪酸的回收率， 能量燃料应该与C-ACC活性的降低平行。C-ACC如何 活性受磷酸化调节， 乳酸和cAMP水平，以及其酶产物丙二酰辅酶A。 丙二酰辅酶A如何调节CPT-I活性将通过以下方法研究： 检查底物和抑制剂相互作用的动力学和CPT-I 对照组和缺氧组心肌细胞对丙二酰辅酶A的敏感性 文化CPT的丙二酰辅酶A敏感亚型位于 肌浆网（SR）将被分离，克隆和表达， 酵母完整组织、培养的心肌细胞和分离的细胞器 将进行免疫学和生化分析， 在对照和缺血损伤组织中的代谢。的存在和 CPT-I不同亚型的位置也将使用 同样的技术与细胞生物学和免疫电子 显微镜 这些实验对于确定亚细胞机制很重要 在正常心脏中调节FAO。没有信息可用 表明C-ACC通过丙二酰- 心脏中的CoA，也没有心肌的任何数据， 描述CPT-I适应性反应作用的肝脏， 生理和病理刺激。确定这些变化 代谢和功能反应的调节机制， 缺血再灌注的心脏将提供与 顿抑心肌的治疗管理，以及关于 缺血后恢复的能量学。

This proposal will study the cellular regulation of fatty acid oxidation (FAO) in ischemic hearts and cultured neonatal rat cardiac myocytes. The role of the cardiac isoform of acetyl-CoA carboxylase (C-ACC) in the cytoplasmic synthesis of malonyl-CoA and the subsequent inhibition of carnitine palmitoyltransferase I (CPT-I) in unknown. Lactate may affect the expression of C-ACC to regulate FAO during ischemia and early reperfusion, conditions in which tissue lactate is elevated. Transient activation of C-ACC by te production of lactate during ischemia may shift oxidative metabolism to the use of carbohydrate when these conditions prevail during early reperfusion. Recovery of fatty acid as an energy fuel should parallel a reduction in C-ACC activity. How C-ACC activity is regulated by phosphorylation will be correlated with tissue levels of lactate and CAMP, and with its enzyme product, malonyl-CoA. How malonyl-CoA modulates CPT-I activity will be investigated by examining the kinetics of substrate and inhibitor interaction and CPT-I sensitivity to malonyl-CoA in control and hypoxic cardiac myocytes in culture. A malonyl-CoA-sensitive isoform of CPT located in the sarcoplasmic reticulum (SR) will be isolated, cloned and expressed in yeast. Intact tissue, cultured cardiac cells, and isolated organelles will be analyzed immunologically and biochemically to examine cardiac metabolism in control and ischemic injured tissue. The presence and location of different isoforms of CPT-I also will be determined using the same techniques together with cell biology and immunoelectron microscopy. These experiments are important for defining the subcellular mechanisms that regulate FAO in the normal heart. No information is available suggesting that C-ACC plays a role in the regulation of FAO by malonyl- CoA in the heart, nor are there any data for cardiac muscles as for liver that describe a role for an adaptive response of CPT-I to physiological and pathological stimuli. Determining the changes in these regulatory mechanisms in the metabolic and functional responses of the ischemic, reperfused heart will provide information relevant to the therapeutic management of the stunned myocardium, and about the energetics of recovery following ischemia.