Influences of Lymph Flow on the Lymphatic Pump

描述(申请人提供)：淋巴系统在体液循环、大分子动态平衡、脂肪吸收和免疫中起重要作用。淋巴水肿是一种常见的淋巴功能障碍，表现多样，发病率较高。淋巴水肿可能与长时间的淋巴流动增强有关。到目前为止，关于血流介导的淋巴反应及其影响的信息非常有限。因此，对淋巴流动调节机制的研究对于发现淋巴水肿的发病机制和有效治疗是极其重要的。建议的总体目标是调查淋巴流动对淋巴收缩功能的影响，并评估这些影响的机制。本研究将集中于：1)定性和定量地评价不同原位条件下淋巴管内淋巴流动和速度的模式和大小。我们将测量大鼠肠系膜淋巴管的淋巴管直径、淋巴压力和速度，在对照条件下，以及在低张容量输注增强淋巴形成/流动期间。在这些研究中将使用伺服零微压、光学测速和视频定格技术。2)研究孤立淋巴管中血流介导的淋巴管收缩功能改变的定量和时间模式。我们将确定分离淋巴管所需的压力分布，以模拟在现场观察到的淋巴压力和速度范围，然后评估在几分钟到几小时的过程中，血流对淋巴管收缩泵功能各个方面的影响的时间模式。计算机控制的伺服泵和乳胶微球(直径约5微米)将被集成到灌流系统中来控制淋巴的压力和速度。3)探讨血流影响淋巴管收缩功能的细胞和分子机制。在孤立的淋巴管实验中，我们将验证血流介导的事件是否依赖于完整的内皮细胞。然后，研究将集中于淋巴管血流介导反应的三种可能的内皮依赖性途径(一氧化氮、前列腺素和内皮依赖性超极化因子)。将使用这3条通路的不同阻滞剂进行研究，以确定这些通路是否以及在多大程度上参与了淋巴收缩功能的血流介导的改变。这些实验的终点将包括测量分离淋巴管中淋巴管内皮细胞和肌肉细胞的细胞内钙，以及淋巴压力、流量、速度、剪切力、壁张力和淋巴管直径。

DESCRIPTION (provided by applicant): The lymphatic system plays important roles in body fluid circulation, macromolecular homeostasis, fat absorption, and immunity. A common lymphatic dysfunction, lymphedema is diversely expressed, and results in significant morbidity. Lymphedema can be associated with the long periods of enhanced lymph flow. Until now, very limited information about flow-mediated lymphatic responses and their impact has been available. Thus investigation of the mechanisms regulating lymph flow is extremely important to ongoing attempts to discover the pathogenesis and the effective treatment of lymphedema. The general objectives of proposal are to investigate the effects of lymph flow on lymphatic contractile function and to evaluate the mechanisms involved in these effects. The proposed studies will focus on: 1) Qualitatively and quantitatively evaluate the patterns and magnitudes of lymph flow and velocity in lymphatics under differing conditions in situ. We will measure lymphatic diameter, lymph pressures and velocities in rat mesenteric lymphatics under control conditions as well as during periods of enhanced lymph formation/flow by hypotonic volumeinfusion. Servo-null micropressure, optical velocimetry and video freeze-frame techniques will be used in these studies. 2) Investigate the quantitative and temporal patterns of flow-mediated alterations in lymphatic contractile function in isolated lymphatics. We will determine the pressure profiles needed in the isolated lymphatic to simulate the range of lymph pressures and velocities observed in situ and then evaluate the temporal pattern of flow-mediated effects on various aspects of lymphatic contractile pump function over the course of minutes to hours. Computerized servo controlled pumps and latex microspheres (about 5 mu m diameter) incorporated into perfusion system will be used to control the lymph pressure and velocities. 3) Investigate the cellular and molecular mechanisms that are responsible for the effects of flow on lymphatic contractile function. In isolated lymphatic experiments we will verify if the flow-mediated events are dependent upon an intact endothelium. Studies will then focus on 3 likely endothelial-dependent pathways (nitric oxide, prostanoid, and endothelial-dependent hyperpolarization factor) of the flow-mediated responses of lymphatics. Studies will be conducted using various blockers of these 3 pathways to determine if and to what degree these pathways might be involved in flow-mediated alteration of lymphatic contractile function. Endpoints of these experiments will include measurement of intracellular calcium of lymphatic endothelial and muscle cells in isolated lymphatics as well as lymph pressure, flow, velocity, shear, wall tension and lymphatic diameter.