Cardioplegia and coronary micorvascular reactivity

描述（由申请人提供）：我们建议检查冠状动脉 和外周微血管反应性，并确定各自的机制 由于体外循环的结果而发生的变化 循环/心肺转流（CPB）和心脏停搏液。这将是 通过研究冠状动脉、肠系膜和 使用体内和体外技术的骨骼肌微循环， 使得自动调节和代谢影响最小化或消除。 标准的细胞和分子方法将用于确定 血管通路发生特殊变化。将采用猪模型 为了确定CPB和心脏停搏液对血管信号转导的影响， 而来自大鼠的分离的微血管将用于检查 血管反应性的特定病理过程。由于CPB和 心脏停搏液固有地涉及许多同时发生的病理过程， 只要有可能，特定的病理过程的影响将是 抑制并评估血管功能的相应变化。体外 还将在完整的分离微血管上进行实验， 负责改变音调操作的信号转导的变化 通过蛋白激酶C（PKC）、促分裂原 活化蛋白激酶和肌球蛋白轻链磷酸化 血管平滑肌中的通路。以下具体目标将是 解决：1）确定负责改变的机制 心停搏液后激动剂诱导的和肌源性的微血管收缩 猪的模型2)研究导致微血管减少的机制 平滑肌肌源性和激动剂诱导的外周（骨骼）收缩 肌肉和肠系膜）微血管。3)检验…的影响 过氧化氢和其它氧化应激增强剂和 氧化应激对PKC介导的离体外周（骨骼和 肠系膜）大鼠血管。此外，我们还将研究先验的影响。 血管暴露于α-1肾上腺素能（苯肾上腺素）、血栓素A2 （U46619）和加压素。4)血管紧张素Ⅱ的血管调节 将在体外检查直接细胞因子暴露的外周微血管。 具体而言，外周微血管将暴露于血小板衍生的 生长因子，血管内皮生长因子，肿瘤坏死因子-α 白细胞介素-6和白细胞介素-8的单独和组合以及在 氧化应激的增加。这些研究应该提供更好的 了解全身性疾病的病因、潜在的预防和治疗 低血压和灌注不良，并可能改善患者的结局（减少 发病率和较短的住院时间）进行心脏手术， 使用哪种CPB支持。最后，考虑到血管扩张的改变 调节和其他病理条件，如增加血管 渗透性通常具有共同的机制，实验结果 本提案中所述可能具有普遍意义。

DESCRIPTION (provided by applicant): We propose to examine changes in coronary and peripheral microvascular reactivity and identify the respective mechanisms of change, which occurs as a consequence of extracorporeal circulation/cardiopulmonary bypass (CPB) and cardioplegia. This will be accomplished by a unique approach to the study of the coronary, mesenteric and skeletal muscle microcirculations using both in vivo and in vitro techniques, such that auto regulatory and metabolic influences are minimized or eliminated. Standard cellular and molecular approaches will be used to determine what specific changes occur in vasomotor pathways. Porcine models will be employed to define the effects of CPB and cardioplegia on vascular signal transduction, while isolated micro vessels from rats will be used to examine the effects of specific pathologic processes on vascular reactivity. Since CPB and cardioplegia inherently involve numerous simultaneous pathologic processes, whenever possible, the effects of specific pathologic processes will be inhibited and the consequent change in vascular function assessed. In vitro experiments on intact isolated micro vessels will also be performed to identify the changes in signal transduction responsible for altered tone operating through conventional and novel isoforms of protein kinase C (PKC), mitogen activated protein (MAP) kinases and myosin light chain (MLC) phosphorylation pathways in vascular smooth muscle. The following specific aims will be addressed: 1) to identify the mechanisms responsible for altered agonist-induced and myogenic microvascular contraction after cardioplegia in the porcine model. 2) To examine the mechanisms causing reduced microvascular smooth muscle myogenic and agonist induced contraction of peripheral (skeletal muscle and mesenteric) micro vessels after CPB. 3) To examine the effects of hydrogen peroxide and other enhancers of oxidative stress and inhibitors of oxidant stress on PKC-mediated contraction in isolated peripheral (skeletal and mesenteric) rat vessels. In addition, we will study the effects of prior exposure of vessels to alpha-1 adrenergic (phenylephrine), thromboxane A2 (U46619), and vasopressin. 4) The relationship of vasomotor regulation of peripheral micro vessels to direct cytokine exposure will be examined in vitro. Specifically, peripheral micro vessels will be exposure to platelet-derived growth factor, vascular endothelial growth factor, tumor necrosis factor-alpha interleukin-6, and interleukin-8 alone and in combination and in the presence of increased oxidative stress. These studies should provide a better understanding of the cause, potential prevention and treatment of systemic hypotension and mal-perfusion and may improve the outcome of patients (reduced morbidity and shorter length of hospitalization) undergoing cardiac surgery in which CPB support is utilized. Finally, given that alterations in vasomotor regulation and other pathological conditions such as increased vascular permeability often share common mechanisms, the findings of the experiments described in this proposal may have universal implications.