CA2+ SIGNALING IN ARTERIAL SMOOTH MUSCLE CELLS

本项目的总体目标是更全面地了解动脉平滑肌细胞内钙离子的稳态和信号传递过程，并研究低氧引起肺血管收缩的机制。与大多数血管床一样，肺动脉的高阻力动脉将分流的血液收缩到肺的氧气充足的区域，而肾动脉则放松，增加流量。通过研究来自肺和肾动脉的平滑肌细胞，可以将肺血管系统特有的机制与更一般的机制区分开来。具体地说，将检验三个假说：1)肺动脉平滑肌细胞(PASMC)的钙稳态是由肌浆网(SR)、线粒体和细胞外钙源之间的相互作用控制的；2)肌浆网(SR)钙释放改变了PASMC的膜电位，低氧调节了这一过程；3)细胞内pH的变化影响了Ca+信号，低氧改变了PASMC的细胞内pH。这些假说将在新鲜分离的犬肺和肾动脉平滑肌细胞中进行验证，使用全细胞和激光共聚焦荧光显微镜，并结合细胞电生理学技术。这项研究将有助于填补关于钙信号过程在肺循环血管反应性中的作用的现有知识空白。其医学意义在于，所获得的结果可能揭示导致肺和全身高血压的重要细胞机制，并可能导致治疗或预防这些疾病的新药和治疗策略的开发。

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.