Conduction and coordination of electrical signals within the lymphatic vascular wall

淋巴管壁内电信号的传导和协调

• 批准号: 9188827
• 负责人: Michael John Davis
• 金额: $ 39.04万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-12-24 至 2018-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9188827
• 关键词: Action Potentials; Address; Affect; Behavior; Blood Vessels; Cell Communication; Cells; Computer Simulation; Connexin 43; Connexins; Coupling; Data; Defect; EFRAC; Endothelial Cells; Endothelium; Exhibits; Gap Junctions; Generations; Genetic study; Human; Hydrostatic Pressure; Impairment; Incidence; Knock-out; Knockout Mice; Knowledge; Limb structure; Link; Location; Lymph; Lymphatic; Lymphatic vessel; Lymphedema; Measures; Mechanics; Mediating; Membrane Potentials; Microelectrodes; Modeling; Mus; Muscle Cells; Mutation; Pacemakers; Patients; Peripheral; Pharmacology; Play; Preparation; Protein Isoforms; Proteins; Proto-Oncogene Protein c-kit; Pump; Reporter; Resistance; Role; Signal Transduction; Site; Smooth Muscle; Smooth Muscle Myocytes; Testing; Tissues; Woman; arteriole; cell dimension; indexing; link protein; lymphatic pump; malignant breast neoplasm; nodal myocyte; pressure; primary lymphedema; public health relevance; Action Potentials; Address; Affect; Behavior; Blood Vessels; Cell Communication; Cells; Computer Simulation; Connexin 43; Connexins; Coupling; Data; Defect; EFRAC; Endothelial Cells; Endothelium; Exhibits; Gap Junctions; Generations; Genetic study; Human; Hydrostatic Pressure; Impairment; Incidence; Knock-out; Knockout Mice; Knowledge; Limb structure; Link; Location; Lymph; Lymphatic; Lymphatic vessel; Lymphedema; Measures; Mechanics; Mediating; Membrane Potentials; Microelectrodes; Modeling; Mus; Muscle Cells; Mutation; Pacemakers; Patients; Peripheral; Pharmacology; Play; Preparation; Protein Isoforms; Proteins; Proto-Oncogene Protein c-kit; Pump; Reporter; Resistance; Role; Signal Transduction; Site; Smooth Muscle; Smooth Muscle Myocytes; Testing; Tissues; Woman; arteriole; cell dimension; indexing; link protein; lymphatic pump; malignant breast neoplasm; nodal myocyte; pressure; primary lymphedema; public health relevance

DESCRIPTION (provided by applicant): Lymph transport relies critically on the intrinsic contractions of lymphatic smooth muscle (SM) cells in the walls of collecting lymphatic vessels to propel lymph against a hydrostatic pressure gradient. These contractions must be coordinated within each pumping unit, the lymphangion, to efficiently propel lymph downstream to the next segment. Synchronized contractions depend on tight electrical coupling of lymphatic SMCs through connexins (Cx) - gap junction proteins that link adjacent cells and allow the transfer of electrical current. The significance of understanding how contractions are coordinated is underscored by studies suggesting that impaired or uncoordinated lymphatic vessel contractions contribute to both congenital and acquired forms of lymphedema. Notably, women with Cx47 mutations have a higher incidence of breast cancer-related lymphedema of the extremities and patients with Cx47 or Cx43 mutations develop primary lymphedema, reputedly due to a contraction coordination deficit in collecting lymphatic vessels. Little is know about Cx expression and electrical coupling between the cells of the lymphatic wall. A better understanding of how electrical signals are conducted and coordinated within and along the lymphatic wall requires knowledge of the specific Cx isoforms expressed in the SM and endothelial cell (EC) layers as well as direct measures of electrical coupling between the cells. We have recently developed a preparation ideally suited to address these issues: the isolated popliteal lymphatic vessel of the mouse. We can control pressure/flow, measure membrane potential in both SMCs and ECs, and quantitatively assess the degree of cell-cell coupling by passing current between two recording microelectrodes at defined separations. Our preliminary data suggest 1) lymphatic vessels show EC-specific expression of Cx37 and Cx43 but SM-specific expression of Cx45; 2) there is robust EC-EC electrical coupling, good SM-SM coupling, but relatively poor SM-EC coupling. This is in stark contrast to what is found in arterioles. Our central hypothesis is that the lymphatic wall exhibits a high degree of SM-SM electrical coupling between, but not across, valves to allow focal generation, conduction and synchronization of action potentials (APs) within lymphangions; further, we hypothesize that the SM layer is essentially uncoupled electrically from the EC layer, due to poor SM-EC Cx expression, and is optimized to conduct a depolarizing wave rather than a hyperpolarization wave. This hypothesis will be tested by 3 specific aims: 1) Determine the extent of electrical and Cx coupling between SM and EC cells in the lymphatic wall; 2) Determine which cells of the lymphatic wall initiate electrical pacemaking; 3) Determine the factors controlling the direction and conduction of lymphatic pacemaker waves. We will take advantage of GFP reporter mice and global and tissue-specific knock-outs of specific Cx isoforms. Accomplishment of these aims will advance our understanding of how lymphatic contractions are coordinated, enabling potential pharmacological rescue of the dysfunctional lymphatic pump in lymphedema.

描述（由申请人提供）：淋巴运输批判性地依赖于收集淋巴管的壁中淋巴平滑肌（SM）细胞的内在收缩，以推动淋巴淋巴在静水压力梯度上。这些收缩必须在每个泵单元内协调，以便将淋巴在下一个部分有效推动。同步收缩取决于淋巴SMC通过连接蛋白（CX） - 间隙连接蛋白的紧密电耦合，该蛋白将相邻细胞连接并允许电流转移。研究表明，理解收缩方式如何协调的重要性表明，受损或不协调的淋巴血管收缩会导致先天性和获得形式的淋巴水肿。值得注意的是，患有CX47突变的妇女的肢体与乳腺癌相关的淋巴水肿的发生率更高，CX47或CX43突变患者发生了原发性淋巴水肿，由于收集淋巴管的收缩配位数归因于原发性淋巴水肿。对淋巴壁细胞之间的CX表达和电耦合知之甚少。更好地了解如何在SM和内皮细胞（EC）层中表达的特定CX同工型以及细胞之间电耦合的直接测量。我们最近开发了一种理想解决这些问题的制剂：小鼠的孤立popliteal淋巴管。我们可以控制SMC和EC中的压力/流动，测量膜电位，并通过在定义的分离下传递两个记录微电极之间的电流来定量评估细胞细胞偶联的程度。我们的初步数据表明1）淋巴管显示CX37和CX43的EC特异性表达，但CX45的SM特异性表达； 2）具有强大的EC-EC电耦合，良好的SM-SM耦合，但SM-EC耦合相对较差。这与小动脉中发现的形成鲜明对比。我们的中心假设是，淋巴壁在淋巴管之间表现出高度的SM-SM电耦合，但不允许在淋巴管内进行焦点产生，传导和同步。此外，我们假设由于SM-EC CX表达不佳，SM层基本上是从EC层的电气未耦合的，并且被优化以进行去极化波而不是超极化波。该假设将通过3个特定目的进行检验：1）确定淋巴壁中SM和EC细胞之间的电和CX耦合的程度； 2）确定淋巴壁的哪些细胞会启动电动起搏； 3）确定控制淋巴自动起搏器波的方向和传导的因素。我们将利用特定CX同工型的GFP报告小鼠以及全球和组织特异性敲除。这些目标的实现将促进我​​们对淋巴收缩如何协调的理解，从而使淋巴水肿功能障碍淋巴泵的潜在药理学营救。