CA2+ SIGNALING IN ARTERIAL SMOOTH MUSCLE CELLS

本课题的总体目标是更全面地了解动脉平滑肌细胞中的Ca 2+稳态和信号转导过程，并研究缺氧诱导的肺血管收缩的机制。肺动脉的高阻力动脉收缩分流血液到肺的良好氧合区域，而肾动脉放松增加流量，就像大多数血管床一样。通过研究肺动脉和肾动脉的平滑肌细胞，可以将肺血管系统的特异性机制与更普遍的机制区分开来。具体而言，将检验三个假设：1）肺动脉平滑肌细胞（PASMC）中的Ca ~（2+）稳态是由肌浆网（SR）、线粒体和细胞外Ca ~（2+）源之间的相互作用控制的; 2）Sr Ca ~（2+）释放改变PASMC的膜电位，并且缺氧调节该过程;（3）细胞内pH的变化影响Ca ~（2+）信号转导，缺氧改变PASMC细胞内pH。将使用全细胞和激光共聚焦荧光显微镜结合细胞电生理学技术在新鲜分离的犬肺动脉和肾动脉平滑肌细胞中测试这些假设。这项研究将有助于填补现有的知识空白的作用Ca 2+信号转导过程中的血管反应性的肺循环。医学意义在于，所获得的结果可能揭示了导致肺动脉和全身性高血压的重要细胞机制，并可能导致开发新的药物和治疗策略来治疗或预防这些疾病。

The overall goal of this project is to gain a more complete understanding of Ca2+ homeostasis and signaling processes in arterial smooth muscle cells and to study the mechanism underlying hypoxic induced pulmonary vasoconstriction. The high-resistance arteries of the pulmonary arteries constrict shunting blood to well-oxygenated areas of the lung while renal arteries relax increasing flow, as do most vascular beds. By studying smooth muscle cells from pulmonary and renal arteries, mechanisms specific to the pulmonary vasculature can be discriminated from those that are more general. Specifically, three hypotheses will be tested: 1) That Ca2+ homeostasis in pulmonary arterial smooth muscle cells (PASMC) is governed by interactions between sarcoplasmic reticulum (SR), mitochondria, and extracellular Ca2+ sources; 2) That Sr Ca2+ release alters the membrane potential and that hypoxia modulates this process in PASMC; and 3) That intracellular pH changes affect Ca+ signaling and that hypoxia alters intracellular pH in PASMC. These hypotheses will be tested in freshly isolated canine pulmonary and renal arterial smooth muscle cells using whole-cell and laser-confocal fluorescence microscopy in combination with cell electrophysiology techniques. This study will help fill an existing gap in knowledge regarding the role of Ca2+ signaling processes in vascular reactivity of the pulmonary circulation. The medical significance is that the results obtained may reveal important cellular mechanisms responsible for pulmonary and systemic hypertension and could lead to the development of new drugs and therapeutic strategies to treat or prevent these conditions.