MECHANOENERGETICS OF HYPERTROPHY AND FAILURE

肥大和失效的机械能量学

• 批准号: 2607135
• 负责人: MARTIN M LEWINTER
• 金额: $ 29.57万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-05-01 至 2002-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2607135
• 关键词: adenosinetriphosphatase; alkaline phosphatase; bioenergetics; biomechanics; enzyme activity; gel electrophoresis; heart contraction; heart electrical activity; heart enlargement; heart metabolism; isolation perfusion; laboratory rat; microfilaments; myofibrils; myosins; protein isoforms; troponin; ventricular hypertrophy; western blottings

DESCRIPTION: (Adapted from the Investigator's Abstract) The overall goal of this research is to understand the mechanisms for depressed crossbridge cycling in the intact ventricle in chronic overload states in particular during the transition from compensatory hypertrophy to cardiac failure. Depressed crossbridge cycling caused by reduced myofibrillar ATPase activity is a key abnormality in overloaded myocardium. To investigate the mechanisms underlying the transition from compensatory left ventricular hypertrophy to failure, the relationship between LV mechanoenergetics and contractile proteins in experimental models of cardiac hypertrophy with transition to heart failure will be studied. The basis for this hypothesis is from preliminary data in DSS rats, where the transition from compensatory LV hypertrophy to cardiac failure is associated with depressed Emax and increased contractile efficiency and economy. These changes, which are closely linked to myofibrillar ATPase activity, cannot be explained solely on the basis of isomyosin switching (V1 to V3) but are temporally correlated with altered expression of troponin T isoforms. The following hypotheses are suggested: (1) Contractile efficiency and economy are tightly correlated with depressed crossbridge cycling as assessed in skinned strips, (2) a component of depressed ATPase activity is caused by altered thin filament regulation as assessed by in vitro motility assay, and (3) the molecular mechanism that accounts for depressed crossbridge cycling are alterations in thin filament isoform expression and contractile protein phosphorylation. Ventricular mechanoenergetics expressed as the inverse slope of VO2-PVA relation and inverse slope of VO2-forced time interval relation in isolated perfused hearts will be measured and correlated to alterations in crossbridge kinetics (assessed by actomyosin ATPase rate and frequency of maximal oscillatory work (Fmax) in skinned myocardial strips) and correlated to changes in velocity, ATPase rate and force production of myosin interacting with native thin filaments (in vitro motility assay). Changes in TnT protein isoform switching and phosphorylation in addition to TnI and Tm protein levels will be measured by immunoblotting and 2D gel electrophoresis in the presence and absence of alkaline phosphatase.

描述：（根据调查员的摘要进行了改编）的总体目标 这项研究是要了解凹陷Crossbridge的机制 尤其是慢性超负荷状态的完整心室循环 在从补偿性肥大到心脏衰竭的过渡期间。 由肌原纤维ATPase活性减少引起的凹陷的Crossbridge自行车 是心肌超载的关键异常。 调查 从补偿性左心室过渡的基础机制 肥大到失败，LV机械能和 在心脏肥大实验模型中的收缩蛋白与 将研究过渡到心力衰竭。 该假设的基础 来自DSS大鼠的初步数据，其中从代偿性转变 LV肥大到心脏衰竭与EMAX抑郁症和 收缩效率和经济提高。 这些变化是 与肌原纤维ATPase活动密切相关，不能仅仅解释 根据异肌球蛋白切换（V1至V3），但在时间上相关 随着肌钙蛋白T同工型的表达改变。 以下假设 建议：（1）收缩效率和经济紧张 与肤色的凹陷桥骑自行车相关， （2）ATPase活性抑郁症的成分是由变化的变化引起的 通过体外运动测定评估的细丝调节，（3） 解释Crossbridge骑自行车的分子机制是 薄丝同工型表达和收缩蛋白的改变 磷酸化。 心室机械工具表示为逆 VO2-PVA关系的斜率和VO2福利时间间隔的逆斜率 将测量孤立的灌注心脏的关系 Crossbridge动力学的改变（通过肌动蛋白ATPase速率和 皮肤心肌条中最大振荡工作（FMAX）的频率） 并与速度，ATPase速率和力产生的变化相关 肌球蛋白与天然细丝（体外运动测定法）相互作用。 TNT蛋白同工型开关和磷酸化的变化除 TNI和TM蛋白水平将通过免疫印迹和2D凝胶测量 在存在和不存在碱性磷酸酶的情况下电泳。