Unmasking Conduction Deficits in the Scn5a+/- Mouse Model of Brugada Syndrome

项目摘要 Brugada综合征（BrS）是一种罕见但严重的疾病，可导致心律失常和心脏性猝死， 没有结构性心脏病的儿童和年轻人。这种疾病最突出的遗传因素 是scn 5a的功能缺失突变，scn 5a是编码电压门控钠通道Nav1.5的基因。然而，在这方面， 许多具有这些突变的BrS患者在经历重大的血液病事件之前没有症状， 这种综合征在本质上是“隐蔽”的。虽然诊断药物的挑战存在于那些高风险成为 有症状，阳性预测值低。Nav1.5缺失与传导的关系 慢，心律失常是很好的建立，这是可能的，隐藏的传导减慢是 BrS病理学的潜在驱动因素。该提议旨在利用BrS的scn 5a杂合小鼠模型， 确定在完整心脏内的肝纤维化耦合的调制是否可以揭示BrS相关的 传导减慢在目标1中，将通过改变perinexus的宽度来操纵ephaptic耦合， 在分离的、Langendorff灌注的Scn 5a +/-和WT小鼠心脏中，图1显示了闰盘的纳米结构域。 将使用光学标测评估传导速度，其中用电压灌注完整心脏 敏感染料并以高时空分辨率成像。弗吉尼亚理工大学的罗布·古迪博士将提供 技术指导，而研究员学习透射电子显微镜技术。接着她会 采用这种技术来确认会阴宽度的变化。该组件的长期目标是开发 BrS的新诊断方法。本提案的目标2将研究低钠血症是否可以揭示更大的 在Sn 5a +/-小鼠心脏中相对于其WT对应物的传导减慢。同样，研究人员将利用光学 标测以评估响应于该变化的传导。她最近与马特博士的实验室合作， 凯在乔治华盛顿大学学习如何建立和实施浮动微电极，并将 我继续与这个小组合作，以便在Fralin生物医学中心Poelzing博士的实验室建立这项技术。 弗吉尼亚理工大学卡内基研究所（FBRI）。浮动微电极技术将提供稳定的， 直接电生理测量从完整的，跳动的小鼠心脏对低钠血症的反应。很长的- 这一部分的长期目标是评估监测BrS患者的血浆钠和钙水平是否 可能是预防BrS临床表现的有效方法。总之，这项提议的结果 可能为BrS的新诊断和治疗提供新的研究途径。所有提出的 实验将在FBRI进行，FBRI是弗吉尼亚理工大学的合作生物医学研究校园。与 在她的赞助商和指导团队的支持下，该项目也将成为扩大和加强 研究员的技术和专业技能，以便为她的职业生涯规划的下一步做好准备， 博士后助理正在成为心脏电生理学领域的独立研究员。

Project Summary Brugada Syndrome (BrS) is a rare but severe disease that can lead to arrhythmias and sudden cardiac death in children and young adults with no structural heart disease. The most prominent genetic contributor to this disease is loss of function mutations in scn5a, the gene encoding the voltage gated sodium channel, Nav1.5. However, many BrS patients with these mutations are asymptomatic until experiencing a major arrhythmic event, making this syndrome “concealed” in nature. While diagnostic drug challenges exist for those at high risk of becoming symptomatic, they have low positive predictive value. The relationship between loss of Nav1.5, conduction slowing, and arrhythmias is well established, and it is possible that concealed conduction slowing is the underlying driver of BrS pathology. This proposal aims to utilize a scn5a heterozygous mouse model of BrS to determine whether modulation of ephaptic coupling within the intact heart can unmask BrS-associated conduction slowing. In Aim 1, ephaptic coupling will be manipulated by altering the width of the perinexus, a nanodomain of the intercalated disk, in the isolated, Langendorff-perfused Scn5a+/- and WT mouse heart. Conduction velocity will be assessed using optical mapping, wherein the intact heart is perfused with a voltage sensitive dye and imaged with high spatio-temporal resolution. Dr. Rob Gourdie at Virginia Tech will provide technical mentorship while the fellow learns the technique of transmission electron microscopy. She will then employ this technique to confirm changes in perinexal width. The long-term goal for this component is to develop a novel diagnostic for BrS. Aim 2 of this proposal will investigate whether hyponatremia can unmask greater conduction slowing in the Sn5a+/- mouse heart relative to its WT counterpart. Again, the fellow will utilize optical mapping to assess conduction in response to this change. She has recently collaborated with the lab of Dr. Matt Kay at George Washington University to learn how to build and implement floating microelectrodes, and will continue to work with this group in order establish this technique in Dr. Poelzing's lab at the Fralin Biomedical Research Institute at Virginia Tech Carilion (FBRI). The floating microelectrode technique will provide stable and direct electrophysiological measures from intact, beating mouse hearts in response to hyponatremia. The long- term goal for this component is to assess whether monitoring plasma sodium and calcium levels in BrS patients may be an effective approach to prevent clinical manifestations of BrS. Together, the results of this proposal may suggest new avenues of investigation for novel diagnostics and treatments for BrS. All of the proposed experiments will be conducted at FBRI, the collaborative biomedical research campus of Virginia Tech. With the support of her sponsor and mentoring team, this project will also be the basis to expand and strengthen the fellow's technical and professional skill sets in order to prepare her for the next step in her career plan as a postdoctoral associate en route to becoming an independent researcher in the field of cardiac electrophysiology.