Targeting Parenchymal Arterioles in Acute Stroke Treatment

急性中风治疗中的靶向实质小动脉

• 批准号: 9266499
• 负责人: Marilyn J Cipolla
• 金额: $ 34.13万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2020-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9266499
• 关键词: Acute; Affect; Alteplase; Anastomosis - action; Angiotensin II; Animals; Architecture; Arteries; Blood capillaries; Blood flow; Brain; Calcium; Calcium-Activated Potassium Channel; Cerebrovascular Disorders; Cerebrovascular system; Chronic; Clinical; Clinical Trials; Coagulation Process; Comorbidity; Complementary therapies; Core-Binding Factor; Development; Endothelin-1; Excision; Functional disorder; Goals; Hour; Human; Hypertension; Impairment; Infarction; Injury; Ischemia; Ischemic Stroke; Knowledge; L-Type Calcium Channels; Lead; Measures; Membrane; Membrane Potentials; Muscle Tonus; Neuroprotective Agents; Outcome; Oxidative Stress; Pathway interactions; Patients; Perfusion; Peroxonitrite; Phosphotransferases; Potassium; Potassium Channel; Production; Protein Kinase C; Publishing; Rattus; Reperfusion Therapy; Resistance; Resolution; Risk Factors; Role; Site; Smooth Muscle; Stroke; Testing; Time; Tissues; Vascular blood supply; Vasoconstrictor Agents; Vasodilation; acute stroke; arteriole; base; capillary; constriction; endothelial dysfunction; functional status; improved outcome; inward rectifier potassium channel; middle cerebral artery; neuroprotection; parenchymal arterioles; prevent; public health relevance; response; restoration; rho; stroke therapy; stroke treatment; success; thrombolysis; vasoconstriction

 DESCRIPTION (provided by applicant): The global burden of stroke is substantial and growing, yet our ability to treat acute ischemic stroke is severely limited. Although considerable effort has been made in the past 2 decades, neuroprotective agents for treatment of acute stroke have largely failed in clinical trials. The success of thrombolysis and endovascular treatment demonstrates that rapid reperfusion of the ischemic brain is an effective means to prevent injury; however, these therapies are currently limited by a short time window for which it provides benefit and low rates of reperfusion. The long-term goal of this project is to understand how post-ischemic reperfusion affects brain parenchymal arterioles (PAs) - high resistance pre-capillary vessels - in ways that would limit blood flow to the ischemic region, increase perfusion deficit, and promote expansion of infarct. Our central hypothesis is that ischemia and reperfusion (I/R) cause excessive vasoconstriction of PAs that promotes incomplete reperfusion and restriction of capillary flow. We further hypothesize that chronic hypertension, a common co- morbid condition of stroke patients, increases PA vasoconstriction and impairs vasodilation through endothelial dysfunction, restricting reperfusion and worsening stroke outcome. These hypotheses are based on our preliminary studies that demonstrate that unlike middle cerebral arteries that undergo prolonged vasodilation in response to I/R, PAs have enhanced tone due to calcium sensitization of PA smooth muscle. Constriction of PAs is associated with diminished reperfusion, leading us to hypothesize that increased small vessel resistance during I/R is an important contributor to incomplete reperfusion and expansion of infarct. Thus, Aim 1 is to investigate mechanisms of PA vasoconstriction during I/R and its relationship to infarct expansion. We will determine the relationship between PA vasoconstriction and perfusion deficit during I/R, and investigate mechanisms by which I/R promote smooth muscle calcium sensitization, including oxidative stress activation of Rho A kinase and protein kinase C. Our preliminary studies using spontaneously hypertensive stroke prone rats (SHRSP) found that PAs have increased tone prior to and after stroke that is associated with impaired endothelial potassium channel function, including small- and intermediate-conductance calcium-activated (SKCa/IKCa) and inward rectifier (Kir) potassium channels that may be central to vasodilation and increasing reperfusion blood flow. Thus, Aim 2 is to investigate mechanisms by which hypertension enhances PA vasoconstriction and perfusion deficit. We will determine the relationship between PA tone, smooth muscle calcium and membrane depolarization during hypertension and the role of angiotensin II in increasing L-type calcium channel activity and endothelin-1 production. We will also investigate mechanisms of potassium channel dysfunction in PAs during hypertension and their role in impaired vasodilation and infarction. The proposed studies will provide critically needed information on PA dysfunction during I/R and hypertension that is likely to be vital in relation to development of new but effective stroke therapy.

 描述（由申请人提供）：卒中的全球负担是巨大的，并且正在增长，但我们治疗急性缺血性卒中的能力受到严重限制。尽管在过去的20年中已经做出了相当大的努力，但用于治疗急性卒中的神经保护剂在临床试验中基本上失败。溶栓和血管内治疗的成功证明，缺血性脑的快速再灌注是预防损伤的有效手段;然而，这些治疗目前受到其提供益处的时间窗短和再灌注率低的限制。该项目的长期目标是了解缺血后再灌注如何影响脑实质小动脉（PA）-高阻力毛细血管前血管-以限制缺血区域的血流，增加灌注不足，并促进梗死扩大。我们的中心假设是，缺血和再灌注（I/R）引起过度的血管收缩的PA，促进不完全再灌注和毛细血管流动的限制。我们进一步假设，慢性高血压是卒中患者的常见共病，通过内皮功能障碍增加PA血管收缩并损害血管舒张，限制再灌注并恶化卒中结局。这些假设是基于我们的初步研究，表明不像大脑中动脉，经历长期的血管舒张反应I/R，PA具有增强的张力，由于钙敏感的PA平滑肌。PA的收缩与再灌注减少有关，这使我们假设I/R期间小血管阻力增加是不完全再灌注和梗死扩大的重要因素。因此，目的1是研究在I/R过程中PA血管收缩的机制及其与梗死扩展的关系。我们将确定I/R期间PA血管收缩和灌注缺陷之间的关系，并研究I/R促进平滑肌钙敏感化的机制，包括Rho A激酶和蛋白激酶C的氧化应激激活。我们使用自发性高血压卒中易感大鼠（SHRSP）进行的初步研究发现，PA在卒中前后的张力增加，这与内皮钾通道功能受损相关，包括小电导和中电导钙激活（SKCa/IKCa）和内向整流（Kir）钾通道，这些通道可能是血管舒张和增加再灌注血流量的核心。因此，目的2是研究高血压增强PA血管收缩和灌注不足的机制。我们将确定高血压期间PA张力、平滑肌钙和膜去极化之间的关系，以及血管紧张素II在增加L型钙通道活性和内皮素-1产生中的作用。我们也将研究高血压时PA钾通道功能障碍的机制及其在血管舒张受损和梗死中的作用。拟议的研究将提供I/R和高血压期间PA功能障碍的急需信息，这可能对开发新的但有效的卒中治疗至关重要。