PRECONDITIONING: PMN ADHESION AND MICROVASCULAR INJURY

描述：(来自应用程序的逐字)：最近的一些结果 研究表明，短暂的缺血发作增加了对 骨骼肌和其他组织的有害作用更持久 24小时后暴露于缺血和再灌注(IR)，这是一种现象 至AS延迟或晚期缺血预适应(Delay IPC)。虽然 预适应减轻缺血后组织损伤的机制是 不清楚，我们实验室的初步数据表明，延迟的IPC 通过抑制白细胞黏附预防IR所致的肌肉坏死 第二次缺血损伤后再灌流期间的移行。然而， 在以下期间启动的事件链接机制 缺血预适应对缺血后微血管减少的影响 功能障碍和心肌细胞坏死尚不清楚。因此，该委员会的总体目标是 本申请中概述的项目将确定通过哪些机制 延迟IPC减少氧化剂的产生、P-选择素的表达、白细胞 微血管屏障与毛细血管后小静脉的黏附和迁移 骨骼肌中的断裂、毛细血管无复流和心肌细胞坏死 随后在24小时后暴露于长时间的缺血再灌注(IR)。 我们假设一氧化氮(NO)在延迟的IPC中起关键作用， 最初充当触发器，然后随后充当 保护。为了解决这个问题，我们建议确定：(1)否 内皮来源的一氧化氮合酶是在预适应期间产生的 缺血触发延迟性缺血预适应的保护作用；(2)eNOS活性 是由重复过程中产生的增加的剪应力刺激的 在每个IPC周期后解除咬合时发生的高血症 IPC诱导的缓激肽释放；(3)缺血再灌流期间产生的NO 缺血预适应启动延迟性缺血预适应的保护作用 黄嘌呤氧化物系氧化剂的生成机制 (4)蛋白激酶C(P-KC)有助于 延迟预适应MG，如果是，如果异构体特异性PKC易位是 由预适应缺血循环中形成的NO诱导；以及(5) 骨骼肌预适应再灌流过程中NO的产生 通过iNOS依赖机制发挥延迟性IPC的保护作用。至 实现这些目标，我们将利用活体内显微方法 量化氧化剂的产生、白细胞的黏附和迁移、微血管 野生型提睾肌蛋白质渗漏和毛细血管无复流 对照组(C57BL16)和缺乏eNOS、iNOS或nNOS的转基因小鼠。这个 延迟性IPC对黄嘌呤氧化酶活性及IR诱导的P-选择素的影响 表达和心肌细胞坏死也将被调查。异构体特异的PKC 易位、一氧化氮合酶mRNA水平、异构体表达和活性 在IPC和HR期间进行检查。拟议的研究不仅应该实质上 提高我们对延迟的IPC减少的机制的理解 大鼠骨骼肌微血管功能障碍和心肌细胞坏死 随后长时间的缺血和再灌注期，但也应该 为药理学方法的发展提供了理论基础 复制其惊人的强大保护作用。

DESCRIPTION: (Verbatim from the application): The results of a number of recent studies indicate that brief episodes of ischemia increase the tolerance of skeletal muscle and other tissues to deleterious effects of a more prolonged exposure to ischemia and reperfusion (IR) 24 hours later, a phenomenon referred to as delayed or late phase ischemic preconditioning (delayed IPC). Although the mechanisms whereby preconditioning reduces postischemic tissue injury are not clear, preliminary data from our laboratory indicates that delayed IPC prevents muscle necrosis induced by IR by inhibiting leukocyte adherence and emigration during reperfusion after the second ischemic insult. However, the mechanisms linking events that are initiated during the period of preconditioning ischemia to the reduction in postischemic microvascular dysfunction and myocyte necrosis are unclear. Thus, the overall goal of the projects outlined in this application is to determine the mechanisms by which delayed IPC attenuates oxidant production, P-selectin expression, leukocyte adhesion to and emigration across postcapillary venules, microvascular barrier disruption, capillary no-reflow, and myocyte necrosis in skeletal muscles subsequently exposed to prolonged ischemia and reperfusion (IR) 24 hours later. We hypothesize that nitric oxide (NO) plays a critical role in delayed IPC, acting initially as a trigger and then subsequently as the mediator of the protection. To address this issue, we propose to determine whether: (1) NO derived from endothelial NOS is produced during the period of preconditioning ischemia and triggers the protective actions of delayed IPC; (2) eNOS activity is stimulated by the increased shear stress that occurs during the repeated hyperemias that occur on release of the occlusion after each cycle of IPC or by IPC-induced bradykinin release; (3) NO produced during the period of preconditioning ischemia initiates the protective effects of delayed IPC by a mechanism that involves the generation of xanthine oxidase derived oxidant species; (4) protein kinase C (P KC) contributes to the beneficial actions of delayed precondition mg and, if so, if isoform-specific PKC translocation is induced by the NO formed during the cycles of preconditioning ischemia; and (5) NO production during reperfusion of preconditioned skeletal muscles contributes to the protective actions of delayed IPC by an iNOS dependent mechanism. To accomplish these aims, we will utilize intravital microscopic approaches to quantify oxidant production, leukocyte adhesion and emigration, microvascular protein leakage, and capillary no-reflow in cremaster muscles in wild-type control mice (C57BLl6) and in transgenic mice lacking eNOS, iNOS or nNOS. The influence of delayed IPC on xanthine oxidase activity and IR induced P-selectin expression and myocyte necrosis will also be investigated. Isoform-specific PKC translocation, NOS mRNA levels, isoform expression, and activities will be examined during IPC and hR. The proposed studies should not only substantially improve our understanding of the mechanisms whereby delayed IPC reduces microvascular dysfunction and myocyte necrosis in skeletal muscles subjected to subsequent prolonged periods of ischemia and reperfusion but should also provide a rationale for the development of pharmacologic approaches that duplicate its remarkably powerful protective effects.