Creatine Kinase Metabolism in Failing Murine Hearts

描述(申请人提供)：这项建议旨在通过小鼠心肌肌酸激酶(CK)来测量和操纵体内心脏流量，以检验心力衰竭(CHF)的能量匮乏假说。正常的心脏收缩功能对ATP的需求是绝对的，而CK反应是心脏的主要能量储备。CHF患者CK代谢物减少，并可预测预后。最近首次直接测量人体心脏中通过CK的ATP流量，发现CHF的CK流量甚至在全球[ATP]丢失之前就显著减少了50%-70%。尽管有这些支持的证据，传统的代谢干预未能增加衰竭心脏的CK池或流量，以直接测试能量饥饿假说。这项应用提出了使用研究人员刚刚开发的新的转基因方法，在基因上过度表达最有可能限制CHF中CK流量的因素，并在体内确定能量和功能后果。具体目标是：1.将新的临床磁共振技术应用于小鼠研究，以评估活体心肌CK代谢物、流量和功能。验证CHF时CK表达增加可增加活体心肌CK流量并改善心功能的假说。为了验证增加肌酸转运蛋白表达将增加CHF患者心肌肌酸、CK流量和机械功能的假说，4。目的：验证有条件的CK基因缺失会加重CHF的发展，而CK挽救将提供保护的假说。这一建议独特地结合了测量活体心脏CK流量的新的非侵入性工具、执行遗传CK操作的新技术、放弃人类CHF特征的相关动物模型，以及最终评估功能后果的复杂手段。这些小鼠研究提供了在人类充血性心力衰竭中不可能的干预措施，并有望为这种流行的、不断增长的疾病提供新的见解。摘要：在美国，心力衰竭是发病率和死亡率的一个重要且不断增长的原因。我们最近对人类心力衰竭的观察指导了这些目前只能在小鼠身上进行的研究。我们将使用最先进的技术来提高衰竭小鼠心脏的能量代谢，看看这是否改善了心脏的收缩，减少了心力衰竭。

DESCRIPTION (provided by applicant): This proposal aims to measure and manipulate in vivo cardiac flux through myocardial creatine kinase (CK) in mice to test the energy starvation hypothesis of heart failure (CHF). The requirement of ATP for normal cardiac contractile function is absolute and the CK reaction is the major energy reservoir of the heart. CK metabolites are reduced in CHF and predict outcomes. The first direct measures of ATP flux through CK in the human heart recently revealed dramatic 50-70% reductions in CK flux in CHF even before global [ATP] loss occurs. Despite this supporting evidence, conventional metabolic interventions have failed to augment CK pools or flux in failing hearts to directly test the energy starvation hypothesis. This application proposes the use of new transfection approaches, just developed by the investigators, to genetically over-express the factors most likely limiting CK flux in CHF and determine, in vivo, the energetic and functional consequences. The specific aims are: 1.) to implement new clinical MR techniques in mouse studies for assessing in vivo cardiac CK metabolites, flux and function, 2.) to test the hypothesis that increasing CK expression in CHF increases in vivo cardiac CK flux and improves ventricular function, 3.) to test the hypothesis that increasing creatine transport protein expression will increase myocardial creatine, CK flux, and mechanical function in CHF, 4.) to test the hypothesis that conditional CK gene deletion will exacerbate the development of CHF and that CK rescue will provide protection. This proposal uniquely brings together novel non-invasive tools to measure in vivo cardiac CK flux, new technology to perform genetic CK manipulations, relevant animal models that capitulate characteristics of human CHF, and finally, sophisticated means to assess the functional consequences. These mouse studies offer interventions not possible in human CHF and promise new insights for this prevalent, growing disease. Lay summary: Heart failure is an important and growing cause of morbidity and mortality in the United States. Our recent observations in human heart failure guide these studies that currently can only be performed in mice. We will use state-of-the-art techniques to increase energy metabolism in failing mouse hearts and see if that improves the contraction of the heart and reduces heart failure.