A novel integrative approach to the comprehensive study of skeletal muscle blood flow

背景：交感神经系统（SNS）是血管功能和健康的重要控制者。这种控制系统通过从神经中释放一种叫做去甲肾上腺素（NE）和神经肽Y （NPY）的化学物质来发挥作用。NE和NPY的主要作用部位在被称为微动脉或微血管的小动脉上。在NE和NPY收缩微血管的同时，内皮细胞（血管内部的细胞）竞相扩张（放松）微血管。值得注意的是，迄今为止，很少有实验模型能够在微血管水平上直接研究NE和NPY对活体动物的影响。事实上，目前还没有人研究SNS和内皮系统从进料血管到毛细血管床同时作用的情况。目的：我们将开发一种新的大鼠骨骼肌制剂，以实时表征NE和NPY对小动脉树各水平的影响。此外，我们将研究内皮细胞如何与NE和NPY相互作用，无论是单独作用还是共同作用。本研究的数据将提供有关SNS和内皮对小动脉控制和小动脉和毛细血管中红细胞分布的影响的新的和有价值的信息。方法：在静息条件下，使用血管收缩和舒张药物，在显微镜下直接观察微血管。我们将在显微镜下拍摄各级血管和红细胞的视频，并使用专门设计的软件，我们将：1)表征NE和NPY对微血管血流的影响，从饲料动脉到毛细血管；2)区分NE和NPY对红细胞分布的影响；3)内皮如何影响NE和NPYs的功能作用。意义：该模型产生的数据将提供有关内皮、NE和NPY对微血管的完整和综合作用的第一手信息。除了对骨骼肌血流和血流动力学的控制获得新的和直接的见解外，这个实验数据将证实和建立我们目前在骨骼肌组织血流和氧运输的数学建模方面的部门努力。

BACKGROUND: The sympathetic nervous system (SNS) is an important controller of vascular function and health. This control system exerts its effects by releasing chemicals from nerves called norepinephrine (NE) and neuropeptide Y (NPY). A major site of action for the NE and NPY is on small arteries called arterioles or microvessels. At the same time as NE and NPY constrict microvessels, the endothelium (cells on the inside of vessels) competes to dilate (relax) them. Remarkably, as of yet, few experimental models have been developed to directly examine the effects of NE and NPY in live animals at the microvascular level. In fact, no one has studied the SNS and endothelial systems acting together from feed vessel to capillary bed at one time. OBJECTIVES: We shall develop a new rat skeletal muscle preparation to characterize the impact of NE and NPY, on all levels of the arteriolar tree, in real-time. Furthermore, we will investigate how the endothelium interacts with NE and NPY, on their own and together. Data generated from this research will provide new and valuable information pertaining to the impact of the SNS and the endothelium on arteriolar control and red blood cell distribution in arterioles and capillaries. APPROACH: We shall directly observe the microvasculature using a microscope, under resting conditions, and with drugs that constrict and relax vessels. From the microscope we will take videos of the blood vessels and red blood cells at all levels, and using specially designed software we will: 1) characterize the impact of NE and NPY on microvascular blood flow, from feed arteries to capillaries; 2) differentiate the influence of NE and NPY on red blood cell distribution; and 3) describe how the endothelium can impact NE and NPYs functional role. SIGNIFICANCE: The data generated from this model will provide first hand information pertaining to the complete and combined role of the endothelium, NE, and NPY on the microvasculature. Besides gaining new and direct insight into the control of skeletal muscle blood flow and hemodynamics, this experimental data will confirm and build on our current departmental efforts in mathematical modeling of skeletal muscle tissue blood flow and oxygen transport.