ITO IN DOGS WITH INHERITED VENTRICULAR ARRHYTHMIAS

患有遗传性室性心律失常的狗中的 ITO

• 批准号: 6639830
• 负责人: BRUCE G KORNREICH
• 金额: $ 9.41万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-15 至 2006-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6639830
• 关键词: arrhythmia; beta adrenergic receptor; congenital heart disorder; dogs; enkephalins; gene expression; heart innervation; heart ventricle; muscle cells; nerve growth factors; norepinephrine; potassium channel; protein isoforms; second messengers; sympathetic nervous system; voltage /patch clamp; western blottings

Abnormalities of ventricular repolarization have been identified in a number of cardiac disease states and may predispose to malignant or fatal ventricular arrhythmias. The transient outward potassium current, I- to, is an important determinant of ventricular repolarization. The potassium channel isoform responsible for I-to varies between species. Kv1.4, Kv1.5, Kv4.2, and Kv4.3 have been identified as contributors to ventricular repolarization in various species, with Kv1.4, Kv4.2, and Kv4.3 representing the most likely contributors to I-to in canine cardiac myocytes. Decreased I-to density has been found in several pathologic states including myocardial hypertrophy, terminal heart failure, and acute Trypanosoma cruzi infection, and prolonged ventricular repolarization may increase the morbidity and mortality of these conditions. Moise and collaborators have previously reported a line of German Shepherd dogs with inherited ventricular arrhythmias and sudden death. Affected dogs have a decreased sympathetic innervation of the left ventricle and decreased left ventricular I-to density. Norepinephrine application rescues I-to in myocytes isolated from affected regions in these dogs, suggesting that the decreased I-to may result from a loss of the trophic influence of the sympathetic nervous system during development. Nerve growth factor and enkephalins have been shown to promote growth and survival of central and peripheral neurons. Using whole cell patch clamp recording ribonuclease protection assays, and Western blot techniques, we will address the following questions: (1) Is decreased NGF and ppENK expression responsible for the abnormal peripheral sympathetic innervation in the hearts of affected dogs? (2) Which potassium channels (Kv1.4, Kv1.5, Kv4.2, and Kv4.3) are responsible for I-to in affected dogs? Is the decreased expression of one or a combination of these channel isoforms responsible for deceased I-to in affected dogs? Is the increased expression of one or a combination of these isoforms responsible for NE mediated restoration of I-to in affected dogs?, and (3) Is the restoration of I-to by NE in the hearts of affected dogs mediated by alpha or beta adrenergic receptors and their associated second messenger cascades? The scientific training obtained while performing this research in a vital and supportive intellectual environment will provide valuable theoretical and technical experience for the applicant to expand upon his clinical and basic scientific experience to achieve his goal of a link between the basic scientific study of membrane bound ion channels/receptors and clinical cardiology.

心室复极异常已在多种心脏病状态下被发现，并可能诱发恶性或致命性室性心律失常。瞬时外向钾电流 I-to 是心室复极的重要决定因素。负责 I-to 的钾通道亚型因物种而异。 Kv1.4、Kv1.5、Kv4.2 和 Kv4.3 已被确定为不同物种心室复极的贡献者，其中 Kv1.4、Kv4.2 和 Kv4.3 代表 I-to 最可能的贡献者在犬心肌细胞中。在多种病理状态下，包括心肌肥厚、终末心力衰竭和急性克氏锥虫感染，已发现 I-to 密度降低，而心室复极时间延长可能会增加这些疾病的发病率和死亡率。莫伊兹和合作者此前曾报道过一系列患有遗传性室性心律失常和猝死的德国牧羊犬。受影响的狗左心室交感神经支配减少，左心室 I-to 密度降低。去甲肾上腺素的应用可以挽救从这些狗受影响区域分离出的肌细胞中的 I-to ，这表明 I-to 的减少可能是由于发育过程中交感神经系统营养影响的丧失所致。神经生长因子和脑啡肽已被证明可以促进中枢和外周神经元的生长和存活。使用全细胞膜片钳记录核糖核酸酶保护测定和蛋白质印迹技术，我们将解决以下问题：（1）NGF和ppENK表达减少是否是受影响狗心脏中外周交感神经支配异常的原因？ (2) 哪些钾通道（Kv1.4、Kv1.5、Kv4.2 和 Kv4.3）负责受影响狗的 I-to？这些通道亚型中的一种或多种的表达降低是否是受影响狗中 I-to 死亡的原因？这些同工型中的一种或多种同工型的表达增加是否导致受影响狗中 NE 介导的 I-to 恢复？以及 (3) 受影响狗心脏中 NE 恢复 I-to 是否由 α 或 β 介导肾上腺素能受体及其相关的第二信使级联？在充满活力和支持性的智力环境中进行这项研究时获得的科学培训将为申请人提供宝贵的理论和技术经验，以扩展其临床和基础科学经验，以实现膜结合离子基础科学研究之间的联系的目标通道/受体和临床心脏病学。