Mechanisms of resistance artery contraction

描述(申请人提供)：本提案的主要目的是阐明几种参与调节细胞内钙离子和脑动脉收缩的新介质和机制的功能意义。通过收缩和扩张活动，大脑动脉在维持正常大脑功能的范围内严格调节血流和毛细血管灌流压。我们发现，瞬时受体电位(Trp)超家族离子通道的成员存在于脑动脉中，这些通道在脑血管功能中发挥着新的、特定的和不同的作用：TRPM4辅助机械转导。(目标1)；TRPC3转导血管收缩受体反应(目标2)；TRPV4在内皮/平滑肌通讯中具有独特的作用(目标3)。我们建议阐明这些不同的色氨酸通道在脑血管系统中的特性，并确定它们的血管调节作用。具体目标1：明确TRPM4通道在脑动脉中的特性、信号偶联机制和独特的功能作用。这些实验将揭示天然血管平滑肌中TRPM4通道的生物物理特性，确定其可能的机械敏感性，并考虑其在体内的功能。特定目的2：阐明天然TRPCS通道在激动剂诱导的钙内流和脑血管收缩中的作用和调节。这些实验将证明TRPC3通道作为受体操纵的阳离子通道在血管平滑肌中的可能作用，并阐明控制血管TRPC3活性的机制。具体目的3：明确和区分TRPV4通道在脑动脉中的作用。我们的初步数据表明，TRPV4通道在内皮依赖性血管扩张活性中扮演了一个新的和意想不到的角色，涉及内皮衍生的超极化因子、TRPV4通道和局部钙释放事件(钙火花)。在目标3中，我们将揭示这些反应所涉及的具体机制。使用多种最先进的技术(膜电位、细胞钙、直径、离子通道记录、体内血流测量、基因沉默)以及从分子到整个动物的独特方法组合，将提供对Trp通道在脑循环中作用的全面看法，并为可用于纠正脑血流病理变化的药物指明新的靶点。

DESCRIPTION (provided by applicant): The major objective of this proposal is to elucidate the functional significance of several novel mediators and mechanisms involved in regulating intracellular Ca2+ and contractility of cerebral arteries. Through their constrictor and dilator activity, cerebral arteries tightly regulate blood flow and capillary perfusion pressure within a range that sustains normal brain function. We have discovered that members of the transient receptor potential (TRP) superfamily of ion channels are present in cerebral arteries and that these channels play novel, specific and diverse roles in cerebrovascular function: TRPM4 subserves mechanotransduction. (Aim 1); TRPC3 transduces vasoconstrictor receptor responses (Aim 2); TRPV4 has a unique role in endothelial/smooth muscle communication (Aim 3). We propose to elucidate the properties of these different TRP channels in the cerebral vasculature, and determine their vasoregulatory roles. Specific Aim 1: To define the properties, signal coupling mechanisms, and unique functional roles of TRPM4 channels in cerebral arteries. These experiments will reveal the biophysical properties of TRPM4 channels in native vascular smooth muscle, determine their possible mechanosensitive nature, and consider their in vivo functionality. Specific Aim 2: To elucidate the roles and regulation of native TRPCS channels in agonist induced Ca2+ influx and cerebral vasoconstriction. These experiments will demonstrate the possible role of TRPC3 channels as receptor-operated cation channels in vascular smooth muscle and elucidate the mechanisms by which vascular TRPC3 activity is controlled. Specific Aim 3: To define and differentiate the roles of TRPV4 channels in cerebral arteries. Our preliminary data suggest a novel and unexpected role for TRPV4 channels in endothelium-dependent vasodilator activity, involving endothelium-derived hyperpolarizing factors, TRPV4 channels, and local Ca2+ release events (Ca2+ sparks). In Aim 3 we will reveal the specific mechanisms involved in these responses. The use of multiple, state-of-the-art techniques (membrane potential, cell Ca2+, diameter, ion channel recording, in vivo blood flow measurements, gene silencing) and a unique combination of approaches from the molecular to the whole animal will provide a comprehensive view of the role of TRP channels in the cerebral circulation and indicate novel targets for agents that could be used to correct pathological alterations in cerebral blood flow.