DIETARY PREVENTION OF CARDIAC MITOCHONDRIAL AGING

她的心脏经历了几次与年龄相关的不利变化，导致性能下降，最终导致心力衰竭，这是美国65岁以上老年人的主要死亡原因。氧化损伤、能量供应丧失和组织萎缩被认为是导致心脏功能障碍的潜在因素，随着年龄的增长，这可能是由线粒体衰退引起的。然而，人们对老化心脏线粒体衰退的程度或性质以及改善线粒体衰退的膳食补充剂是否改善心脏功能知之甚少。一些关于线粒体衰变的研究是使用分离的线粒体进行的，但结果相互矛盾，难以解释。这主要是由于一个技术问题：在从老化组织中分离的过程中，线粒体大量溶解和损坏。我们建议对老年和年轻大鼠完整的新鲜分离的心肌细胞的线粒体功能进行表征和比较。方法学的进步使得分析完整细胞内的线粒体功能成为可能，我们现在有初步证据表明，线粒体衰变发生在老年大鼠分离的心肌细胞中。方法学的进步使得分析完整细胞内的线粒体功能成为可能，我们现在有初步证据表明，线粒体衰变发生在从老年大鼠分离的心肌细胞中。因此，这项建议中要解决的问题是：A)心肌细胞线粒体随年龄增长衰退的性质和程度是什么？B)线粒体衰变会影响心脏功能吗？C)喂养老年大鼠的乙酰基-L肉碱(ALCAR)和(R)-硫辛酸(LA)，这两种我们展示的增强线粒体功能和抑制线粒体氧化剂的化合物是否也能改善心肌细胞的线粒体功能？1)研究和比较幼年、成年、成熟和老年大鼠心肌细胞线粒体的功能。特征将包括静止细胞和刺激收缩的心肌细胞的耗氧特性、生物能量和心磷脂含量。其他使用分离的心肌细胞或分离的灌流心脏的研究将确定线粒体衰退对心脏功能的影响。2)检测线粒体抗氧化剂、氧化剂产生和心肌氧化损伤与年龄相关的变化。这些研究不仅有助于确定线粒体衰变对氧化剂产生的影响，而且还有助于确定线粒体产生对整个细胞的影响。3)评估喂饲大鼠ALCAR和/或LA是否能改善线粒体功能，降低心肌细胞的氧化应激，改善心功能。这些实验将测量与特定目标1和2中相同的实验终点。因此，该项目将是我们长期目标的第一步，即确定线粒体衰退在老化的人类心脏病理中的重要性，以及改善线粒体性能的饮食方案是否可以成为治疗衰老过程中心脏功能障碍的廉价而有效的疗法。

Her heart undergoes several adverse age-related changes that lead to loss of performance and ultimately to heart failure, the major cause of death for people over the age of 65 in the U.S. Oxidative damage, loss of energy supply, and tissue atrophy are thought to be underlying factors causing cardiac dysfunction with age, which in turn are likely caused by mitochondrial decay. However, little is known about the extent or nature of mitochondrial decay in the aging heart and whether dietary supplements that ameliorate mitochondrial decline improves cardiac function. Some studies on mitochondrial decay have been performed using isolated mitochondria, but results are conflicting and difficult to interpret. This is primarily due to a technical problem: extensive mitochondrial lysis and damage during isolation from aged tissue. We proposed to characterize and compare mitochondrial function in intact freshly isolated cardiac myocytes from old and young rats. Advances in methodology now make analysis of mitochondrial function within intact cells feasible, and we now have preliminary evidence that mitochondrial decay occurs in isolated cardiac myocytes from old rats. Advances in methodology now make analysis of mitochondrial functions within intact cells feasible, and we now have preliminary evidence that mitochondrial decay occurs is isolated cardiac myocytes from old rats. Thus, the questions to be addressed in this proposal are A) what is the nature and extent of mitochondrial decay in cardiac myocytes with age? B) does mitochondrial decay affect cardiac function? C) does feeding old rats acetyl-L-carnitine (ALCAR) and (R)-lipoic acid (LA), compounds that we showed to enhance mitochondrial function and quench mitochondrial oxidants in isolated hepatocytes, also improve mitochondrial function in cardiac myocytes? We propose to investigate these questions in 3 specific aims: 1) Characterize and compare mitochondrial functions in isolated cardiac myocytes form young, adult, mature and old rats. Characterization will include oxygen consumption characteristics, bioenergics, and cardiolipin content in quiescent cells and in myocytes stimulated to contract. Other studies using isolated cardiac myocytes or isolated perfused hearts will determine the consequences of mitochondrial decay to cardiac performance. 2) Examine age-related changes in mitochondrial antioxidants, oxidant production, and myocardial oxidative damage. These studies will be instrumental in determining not only the impact of mitochondrial decay on oxidant production, but also the effect of mitochondrial production on the cell as a whole. 3) Assess whether feeding rats ALCAR and/or LA improves mitochondrial function, lowers oxidative stress in cardiac myocytes and improves cardiac performance. These experiments will measure the same experimental end-points as in specific aims 1 and 2. This project will thus be the first step in our long term goals of determining the importance of mitochondrial decay in pathologies of the aging human heart and whether dietary regimens that improve mitochondrial performance can be inexpensive yet effective therapies for cardiac dysfunction in aging.