Cellular Mechanisms of Vasoregulation by Volatile Anesthetics

描述(申请人提供)：双孔结构域K+通道(K2P通道)代表吸入麻醉剂对神经元作用的靶点。血管床上K2P通道的特征是来自肺和肠系膜动脉的报道很少。我们最近发现，ATP刺激K+电流，这种电流对主要的K+通道阻滞剂具有抵抗力，而对pH和锌敏感。此外，我们的初步数据表明，这一电流通过K2P通道，这些通道可能调节血管直径。这是一项新的发现，将K2P通道定位为吸入麻醉剂在脑动脉的潜在靶点。我们的总体工作假设是，挥发性麻醉剂激活血管肌细胞中的K2P通道，从而扩张动脉。吸入麻醉剂将激活K2P通道，这取决于它们的开放概率。使用电生理、药理学、成像和血管张力测量的组合，我们将在以下特定目标中检验这一假说。具体目的1：确定胸主动脉和大脑中动脉阻滞剂K2P样电流的药理作用。为此，我们建议用药理学工具证明阻滞剂被酸性和刺激的碱性pH抑制的阻断性全细胞外向电流具有K+选择性，并由K2P样通道携带。1)已知的K2P通道阻滞剂是否能降低胸主动脉和大脑中动脉分离的心肌细胞K+泄漏电流的幅度？2)静息膜电位的哪一部分是由血管细胞中K2P样通道的开放决定的？3)K2P通道阻滞剂对血管内径有何影响？具体目的2：确定吸入麻醉药如何激活K2P样通道，以及吸入麻醉药对血管张力的影响？我们将结合电生理学、药理学和血管张力测量来回答以下问题：1)全麻药是否增加K2P通道电流的幅度？2)全麻药激活K2P通道对血管直径有何影响？3)吸入麻醉药能否增强ATP引起的血管反应？这些研究的结果将描述一种新的信号通路，通过K2P通道调节血管张力。区域特异性K2P通道的药理学特征将导致高血压和中风的新的靶向治疗，并将有利于全身麻醉。 公共卫生相关性：心血管疾病、高血压和中风是美国主要的死亡原因。目前的提案将研究一种新的信号通路，通过K2P通道调节血管张力。区域特异性K2P通道(大脑中动脉和主动脉)的药理学特征应该会导致高血压和中风的新的靶向治疗。这些类型的研究将验证麻醉作用的细胞机制，并可用于开发可能的治疗方案。

DESCRIPTION (provided by applicant): Two-pore-domain K+channels (K2P-channels) represent targets for actions of inhalation anesthetics on neurons. The few reports characterizing K2P channels in vascular beds are from pulmonary and mesenteric arteries. We have recently found that ATP stimulates K+current that is resistant to major K+channel blockers and sensitive to pH and Zn. Furthermore, our preliminary data suggest that this current is through K2P channels and that these channels may regulate vessel diameter. This is a novel finding that positions K2P channels as potential targets of inhalation anesthetics in cerebral arteries. Our overall working hypothesis is that volatile anesthetics activate K2P channels in vascular myocytes and thereby dilate arteries. Inhalation anesthetics will activate K2P channels depending on their open probability. Using a combination of electrophysiological, pharmacological, imaging and vessel tension measurements, we will test this hypothesis in the following specific aims. Specific Aim 1: To determine pharmacology of blockers-resistive K2P-like currents in thoracic aorta and middle cerebral artery. In this aim, we propose to prove by pharmacological tools that blockers resistive whole cell outward current inhibited by acidic and stimulated basic pH has K+selectivity and is carried by K2P-like channels. 1) Do known K2P-channel blockers decrease amplitude of leak K+currents in myocytes isolated from thoracic aorta and middle cerebral artery? 2) What part of the resting membrane potential is determined by opening of K2P-like channels in vascular myocytes? 3) What is the impact of K2P channel blockers on vessel diameter? Specific Aim 2: To determine how inhalation anesthetics activate K2P-like channels and the impact of inhalation anesthetics on vascular tone? We will use a combination of electrophysiology, pharmacology, and vessel tension measurements to answer the questions: 1) Do general anesthetics increase the amplitude of K2P channel currents? 2) What is the impact of K2P channel activation by general anesthetics on vessel diameter? 3) Can inhalational anesthetics potentiate ATP-elicited vascular responses? The results of these studies will describe a novel signaling pathway regulating vascular tone through K2P channels. Pharmacological characterization of region specific K2P channels should lead to new targeted treatments of hypertension and stroke and will be of benefit for general anesthesia. PUBLIC HEALTH RELEVANCE: Cardiovascular disease, hypertension and stroke are leading causes of death in the U.S. The present proposal will investigate a novel signaling pathway to regulate vascular tone via K2P channels. Pharmacological characterization of region specific K2P channels (middle cerebral artery and aorta) should lead to new targeted treatments of hypertension and stroke. These types of studies will validate cellular mechanisms of anesthetic action and could be used to develop a possible treatment protocol.