Neurogenic Calcium Signals in Small Arteries

小动脉中的神经源性钙信号

• 批准号: 6728132
• 负责人: Withrow Gil Wier
• 金额: $ 29.22万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-02-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6728132
• 关键词: action potentials; adenosine triphosphate; artery; calcitonin gene related peptide; calcium flux; calcium indicator; confocal scanning microscopy; genetically modified animals; laboratory mouse; laboratory rat; membrane potentials; neuromuscular transmission; neuropeptide Y; neuropeptide receptor; norepinephrine; purinergic receptor; receptor binding; receptor expression; vascular smooth muscle nervous control

DESCRIPTION (provided by applicant): The research will focus on the roles and mechanisms of neurogenic Ca 2+ signals in autonomic nervous system control of arterial diameter, particularly the Ca2+ signals generated in smooth muscle cells (SMC) by the concerted action of the sympathetic 'triad' of co-transmitters, ATP, norepinephfine (NE) and neuropeptide Y (NPY). Although components of neurogenic vasoconstriction are attributable to ATP, NE and NPY, the underlying Ca 2+ signals in SMC are not known. Preliminary confocal imaging of Ca 2+ within the SMC of intact pressurized rat mesenteric small arteries during low frequency nerve stimulation has revealed novel Ca2+ transients, putatively associated with excitatory junction potentials (EJPs) and provisionally called "junctional Ca 2+ transients" (jCaTs). With higher frequency stimulation, Ca 2+ 'flashes' (may be due to SMC action potentials) and Ca 2+waves are generated. Stimulation of perivascular sensory nerves elicits vasodilation; preliminary results implicate an increase in the frequency of Ca 2+ sparks. Specific Experimental goals include: 1) Test the hypothesis that jCaTs arise from Ca 2+entering SMCs through P2X1 receptors, which are activated by the ATP contained in one or a few quanta of transmitter, 2) Test the hypothesis that neurally released ATP elicits Ca 2+ influx, but not Ca 2+ waves, 3) Test the hypothesis that neurally released NE elicits Ca 2+ waves that function to activate contraction, 4) Test the hypothesis that neurally released NPY activates the Y1 receptor on SMCS to modulate the effects of NE by changing the frequency of Ca 2+ waves, and 5) Test the hypothesis that calcitonin gene related peptide (CGRP) released from sensory nerves decrease Ca 2+ spark frequency; thus causing vasodilation. Mesenteric small arteries from rats and mice (including a P2Xz-receptor deficient transgenic mouse) will be loaded with fluo-4 and mounted on a confocal myograph for simultaneous Ca2+ imaging, recording of isometric force, and measurement of membrane potential. A real-time confocal microscope will be used to provide 2D images fast enough to resolve jCaTs, flashes and waves. The research will test a comprehensive hypothesis on sympathetic neuromuscular transmission and the control of smooth muscle contraction by the autonomic nervous system: Neurally released ATP activates P2X1 receptors. The resulting Ca 2+ influx activates a small contraction, generates EJPs and is visualized as jCaTs. EJPs may summate to trigger action potentials, visualized as Ca 2+ 'flashes' Neurally released NE and NPY (as metabotropic or G protein-lined receptors) increase the frequency of Ca 2+ waves, which activate strong contraction. By visualizing novel, physiological neurogenic Ca 2+ signals and contraction of intact arteries, the research seeks to provide new information on the concerted action of neurotransmitters in controlling arterial function.

描述（由申请人提供）：研究将重点关注神经源Ca 2+信号在动脉直径的自主神经系统控制中的作用和机制，特别是通过平滑肌细胞（SMC）产生的Ca2+信号，通过同情的“ Triad'co-Triad'co-Triad'co-transmitters，atp，atp，norepinephine）和norepinephfine（neerphe）和Neorpine（Neuroptect）的赋情作用。尽管神经源性血管收缩的成分归因于ATP，NE和NPY，但SMC中的基本Ca 2+信号尚不清楚。在低频神经刺激期间，在完整加压的大鼠肠系膜小动脉的SMC中，Ca 2+的初步共聚焦成像揭示了新型的Ca2+瞬态，与兴奋性连接电位（EJP）相关，并临时称为“汇率Ca 2+瞬态”（JCATS）（JCATS）。使用较高的频率刺激，Ca 2+“闪光”（可能是由于SMC动作电位引起的）和Ca 2+波。刺激血管周神经会引起血管舒张；初步结果暗示Ca 2+火花的频率增加。 Specific Experimental goals include: 1) Test the hypothesis that jCaTs arise from Ca 2+entering SMCs through P2X1 receptors, which are activated by the ATP contained in one or a few quanta of transmitter, 2) Test the hypothesis that neurally released ATP elicits Ca 2+ influx, but not Ca 2+ waves, 3) Test the hypothesis that neurally released NE elicits Ca 2+ waves that function to activate contraction, 4）测试神经释放NPY的假说通过改变Ca 2+波的频率来激活SMC上的Y1受体，以调节NE的影响，5）检验假说，即降钙素基因相关肽（CGRP）从感觉神经中释放出来的假设会降低Ca 2+ Ca 2+ Spark频率；从而导致血管舒张。大鼠和小鼠的肠系膜小动脉（包括P2XZ受体缺陷的转基因小鼠）将用氟-4加载，并安装在共聚焦肌电图上，以同时进行CA2+成像，记录等距力的记录，并测量膜电位。实时共聚焦显微镜将用于提供足够快的2D图像，以解决JCAT，闪光和波浪。这项研究将检验一个关于交感神经肌肉传播的综合假设，以及自主神经系统对平滑肌收缩的控制：神经释放的ATP激活了P2X1受体。所得的Ca 2+涌入会激活一个小收缩，产生EJP，并将其视为JCAT。 EJP可以概括以触发动作电位，可视化为Ca 2+“闪烁”神经释放的NE和NPY（作为代谢性或G蛋白衬里受体）增加了Ca 2+波的频率，从而激活了强收缩。通过可视化新颖的生理神经源CA 2+信号和完整动脉的收缩，该研究旨在提供有关神经递质在控制动脉功能方面的协同作用的新信息。