Calcium signaling in cerebral arteries

描述（由申请人提供）：细胞内钙（Ca 2+）信号传导 事件在空间定位、时间动力学和 生理功能发生在多种细胞类型中。动脉 平滑肌细胞，三种不同类型的细胞内Ca 2+信号传导 已经描述了形态;局部瞬变称为“Ca 2+火花”， 传播事件称为“Ca 2+波”和全球细胞内Ca 2 + [Ca 2 +]i升高。我们实验室的初步数据 提示血管内压力升高Ca 2+火花频率、Ca 2+波 脑动脉平滑肌细胞[Ca ~（2+）]I的变化 稳定的膜去极化，激活电压依赖性Ca 2 + 渠道我们的数据还表明，压力诱导收缩（“肌源性 音调”）通过全球[Ca 2 +]的升高，而火花和波，发生 由于激活的ryanodine敏感的Ca 2+释放（RyR）通道上的 肌浆网（SR），对整体[Ca 2 +]I无显著贡献， 火花和波浪的净效果是对抗收缩。在这 我们将检验血管内压力激活 脑动脉平滑肌细胞内不同钙信号通路 肌细胞通过激活电压依赖性钙通道，并研究 电压依赖性Ca 2+通道与RyR之间的信号传导机制 渠道我们将采用几种最先进的技术，包括激光 扫描共聚焦钙离子成像，比率钙离子成像，膜片钳 电生理学和加压动脉的直径测量。我们 提出三个具体目标。目标1将研究细胞内的调节 脑动脉平滑肌细胞和动脉血管平滑肌细胞内Ca ~（2+）信号通路的研究 血管内压力，并探讨假设，压力 激活钙依赖性钾通道（BKca），诱导细胞内 Ca 2+释放事件。目标2将检验稳定膜 去极化通过升高胞质[Ca 2]i激活Ca 2+火花， SR Ca 2+负荷。目标3将研究假设， 肌膜下[Ca 2 +]I升高引起的开放的电压依赖性 Ca ~（2+）通道激活脑动脉平滑肌细胞中的Ca ~（2+）火花。这 工作将提供一个更好的了解调节和生理 脑动脉平滑肌细胞中Ca 2+信号传导方式的功能。

DESCRIPTION (provided by the applicant): Intracellular calcium (Ca2+) signaling events that differ in respect to spatial localization, temporal kinetics, and physiological function occur in a wide variety of cell types. In arterial smooth muscle cells, three different types of intracellular Ca2+ signaling modalities have been described; localized transients termed "Ca2+ sparks," propagating events termed "Ca2+ waves," and global intracellular Ca2+ concentration ([Ca2+]i) elevations. Preliminary data from our laboratory suggest that intravascular pressure elevates Ca2+ spark frequency, Ca2+ wave frequency and global [Ca2+]I in cerebral artery smooth muscle cells by inducing a steady membrane depolarization that activates voltage-dependent Ca2+ channels. Our data also suggest that pressure induces constriction ("myogenic tone") via an elevation of global [Ca2+] whereas sparks and waves, which occur due to the activation of ryanodine-sensitive Ca2+ release (RyR) channels on the sarcoplasmic reticulum (SR), do not contribute significantly to global [Ca2+]I, and the net effect of sparks and waves is to oppose constriction. In this proposal we will test the hypothesis that intravascular pressure activates different intracellular Ca2+ signaling modalities in cerebral artery smooth muscle cells via activation of voltage-dependent Ca2+ channels and investigate mechanisms of signaling between voltage-dependent Ca2+ channels and RyR channels. We will employ several state-of-the-art techniques including laser scanning confocal Ca2+ imaging, ratiometric Ca2+ imaging, patch clamp electrophysiology, and diameter measurements of pressurized arteries. We propose 3 Specific Aims. Aim 1 will investigate the regulation of intracellular Ca2+ signaling modalities in cerebral artery smooth muscle cells and arterial diameter by intravascular pressure, and explore the hypothesis that pressure activates Ca2+-dependent potassium (BKca) channels by inducing intracellular Ca2+ release events. Aim 2 will examine the hypothesis that steady membrane depolarization activates Ca2+ sparks via an elevation of cytosolic [Ca2]i and SR Ca2+ load. Aim 3 will investigate the hypothesis that localized subsarcolemmal [Ca2+]I elevations caused by the opening of voltage-dependent Ca2+ channels activate Ca2+ sparks in cerebral artery smooth muscle cells. This work will provide a better understanding of the regulation and physiological functions of Ca2+ signaling modalities in cerebral artery smooth muscle cells.