Calcium signaling in cerebral arteries

描述(申请人提供)：细胞内钙(钙)信号 在空间局部性、时间动力学和 生理功能存在于各种各样的细胞类型中。在动脉中 平滑肌细胞，三种不同类型的细胞内钙信号 已经描述了模式；局部化的瞬变称为“钙火花”， 被称为“钙波”的传播事件和全球细胞内钙离子 浓度([Ca2+]i)升高。我们实验室的初步数据 提示血管内压升高钙触发频率，钙波 诱导大鼠脑动脉平滑肌细胞内钙离子的频率和整体[钙]i 一种稳定的膜去极化激活电压依赖性钙离子 频道。我们的数据还表明，压力会导致收缩(“肌源性 音调“)通过全球[Ca~(2+)]升高而产生的火花和波， 由于Ryanodine敏感的钙释放(RyR)通道在 肌浆网(SR)对全球[Ca~(2+)]i无显著贡献， 而火花和波浪的净效果是反对紧缩。在这 我们将检验血管内压激活的假设 不同细胞内钙信号途径在大脑动脉平滑中的作用 肌细胞激活电压依赖性钙通道及其机制的研究 电压依赖性钙通道与RyR之间的信号机制 频道。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3个具体目标。目标1将研究细胞内的调节 大脑动脉平滑肌细胞和动脉中的钙信号转导途径 血管内压的直径，并探索压力的假设 通过诱导细胞内激活钙依赖钾(BKCa)通道 Ca2+释放事件。目标2将检验稳定膜的假设 去极化通过升高胞浆[Ca~(2+)]i和 肌浆网钙负荷。目标3将调查本地化的假设 电压依赖性开放引起的肌膜下[Ca~(2+)]i升高 Ca~(2+)通道激活大脑动脉平滑肌细胞中的钙火花。这 工作将提供更好的了解调节和生理 钙信号通路在大脑动脉平滑肌细胞中的作用。

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.